2 files changed, 10 insertions, 0 deletions

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index a9377fb16c37..293464c0c6ba 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -522,6 +522,7 @@ struct btrfs_fs_info {
         struct work_struct async_submit_work;
         spinlock_t end_io_work_lock;
         spinlock_t async_submit_work_lock;
+        atomic_t nr_async_submits;
 
 #if LINUX_VERSION_CODE <= KERNEL_VERSION(2,6,18)
         struct work_struct trans_work;
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 264f297260f8..373374340e9b 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -453,6 +453,7 @@ int btrfs_wq_submit_bio(struct btrfs_fs_info *fs_info, struct inode *inode,
 
         spin_lock(&fs_info->async_submit_work_lock);
         list_add_tail(&async->list, &fs_info->async_submit_work_list);
+        atomic_inc(&fs_info->nr_async_submits);
         spin_unlock(&fs_info->async_submit_work_lock);
 
         queue_work(async_submit_workqueue, &fs_info->async_submit_work);
@@ -906,10 +907,16 @@ static int btrfs_congested_fn(void *congested_data, int bdi_bits)
 {
         struct btrfs_fs_info *info = (struct btrfs_fs_info *)congested_data;
         int ret = 0;
+        int limit = 256 * info->fs_devices->open_devices;
         struct list_head *cur;
         struct btrfs_device *device;
         struct backing_dev_info *bdi;
 
+        if ((bdi_bits & (1 << BDI_write_congested)) &&
+            atomic_read(&info->nr_async_submits) > limit) {
+                return 1;
+        }
+
         list_for_each(cur, &info->fs_devices->devices) {
                 device = list_entry(cur, struct btrfs_device, dev_list);
                 if (!device->bdev)
@@ -1117,6 +1124,7 @@ static void btrfs_async_submit_work(struct work_struct *work)
                 }
                 next = fs_info->async_submit_work_list.next;
                 list_del(next);
+                atomic_dec(&fs_info->nr_async_submits);
                 spin_unlock(&fs_info->async_submit_work_lock);
 
                 async = list_entry(next, struct async_submit_bio, list);
@@ -1179,6 +1187,7 @@ struct btrfs_root *open_ctree(struct super_block *sb,
         INIT_LIST_HEAD(&fs_info->dirty_cowonly_roots);
         INIT_LIST_HEAD(&fs_info->space_info);
         btrfs_mapping_init(&fs_info->mapping_tree);
+        atomic_set(&fs_info->nr_async_submits, 0);
         fs_info->sb = sb;
         fs_info->max_extent = (u64)-1;
         fs_info->max_inline = 8192 * 1024;