1 files changed, 79 insertions, 0 deletions

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index bb5b3067ddc3..6caddd5970e4 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -2674,15 +2674,94 @@ int btrfs_should_throttle_delayed_refs(struct btrfs_trans_handle *trans,
         u64 num_entries =
                 atomic_read(&trans->transaction->delayed_refs.num_entries);
         u64 avg_runtime;
+        u64 val;
 
         smp_mb();
         avg_runtime = fs_info->avg_delayed_ref_runtime;
+        val = num_entries * avg_runtime;
         if (num_entries * avg_runtime >= NSEC_PER_SEC)
                 return 1;
+        if (val >= NSEC_PER_SEC / 2)
+                return 2;
 
         return btrfs_check_space_for_delayed_refs(trans, root);
 }
 
+struct async_delayed_refs {
+        struct btrfs_root *root;
+        int count;
+        int error;
+        int sync;
+        struct completion wait;
+        struct btrfs_work work;
+};
+
+static void delayed_ref_async_start(struct btrfs_work *work)
+{
+        struct async_delayed_refs *async;
+        struct btrfs_trans_handle *trans;
+        int ret;
+
+        async = container_of(work, struct async_delayed_refs, work);
+
+        trans = btrfs_join_transaction(async->root);
+        if (IS_ERR(trans)) {
+                async->error = PTR_ERR(trans);
+                goto done;
+        }
+
+        /*
+         * trans->sync means that when we call end_transaciton, we won't
+         * wait on delayed refs
+         */
+        trans->sync = true;
+        ret = btrfs_run_delayed_refs(trans, async->root, async->count);
+        if (ret)
+                async->error = ret;
+
+        ret = btrfs_end_transaction(trans, async->root);
+        if (ret && !async->error)
+                async->error = ret;
+done:
+        if (async->sync)
+                complete(&async->wait);
+        else
+                kfree(async);
+}
+
+int btrfs_async_run_delayed_refs(struct btrfs_root *root,
+                                 unsigned long count, int wait)
+{
+        struct async_delayed_refs *async;
+        int ret;
+
+        async = kmalloc(sizeof(*async), GFP_NOFS);
+        if (!async)
+                return -ENOMEM;
+
+        async->root = root->fs_info->tree_root;
+        async->count = count;
+        async->error = 0;
+        if (wait)
+                async->sync = 1;
+        else
+                async->sync = 0;
+        init_completion(&async->wait);
+
+        btrfs_init_work(&async->work, delayed_ref_async_start,
+                        NULL, NULL);
+
+        btrfs_queue_work(root->fs_info->extent_workers, &async->work);
+
+        if (wait) {
+                wait_for_completion(&async->wait);
+                ret = async->error;
+                kfree(async);
+                return ret;
+        }
+        return 0;
+}
+
 /*
  * this starts processing the delayed reference count updates and
  * extent insertions we have queued up so far.  count can be