btrfs: move btrfs_cmp_device_free_bytes to super.c
this function won't be used here anymore, so move it super.c where it is
used for df-calculation
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 0ac712e..32fe8b3 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -913,6 +913,32 @@
return 0;
}
+/* Used to sort the devices by max_avail(descending sort) */
+static int btrfs_cmp_device_free_bytes(const void *dev_info1,
+ const void *dev_info2)
+{
+ if (((struct btrfs_device_info *)dev_info1)->max_avail >
+ ((struct btrfs_device_info *)dev_info2)->max_avail)
+ return -1;
+ else if (((struct btrfs_device_info *)dev_info1)->max_avail <
+ ((struct btrfs_device_info *)dev_info2)->max_avail)
+ return 1;
+ else
+ return 0;
+}
+
+/*
+ * sort the devices by max_avail, in which max free extent size of each device
+ * is stored.(Descending Sort)
+ */
+static inline void btrfs_descending_sort_devices(
+ struct btrfs_device_info *devices,
+ size_t nr_devices)
+{
+ sort(devices, nr_devices, sizeof(struct btrfs_device_info),
+ btrfs_cmp_device_free_bytes, NULL);
+}
+
/*
* The helper to calc the free space on the devices that can be used to store
* file data.