1 files changed, 24 insertions, 0 deletions

diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index a668c0116982..a5cfedf393f9 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -20,8 +20,11 @@
 #define __BTRFS_VOLUMES_
 
 #include <linux/bio.h>
+#include <linux/sort.h>
 #include "async-thread.h"
 
+#define BTRFS_STRIPE_LEN        (64 * 1024)
+
 struct buffer_head;
 struct btrfs_pending_bios {
         struct bio *head;
@@ -137,6 +140,27 @@ struct btrfs_multi_bio {
         struct btrfs_bio_stripe stripes[];
 };
 
+struct btrfs_device_info {
+        struct btrfs_device *dev;
+        u64 dev_offset;
+        u64 max_avail;
+};
+
+/* Used to sort the devices by max_avail(descending sort) */
+int btrfs_cmp_device_free_bytes(const void *dev_info1, const void *dev_info2);
+
+/*
+ * 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);
+}
+
 #define btrfs_multi_bio_size(n) (sizeof(struct btrfs_multi_bio) + \
                             (sizeof(struct btrfs_bio_stripe) * (n)))