Btrfs: show useful info in space reservation tracepoint

o For space info, the type of space info is useful for debug.
o For transaction handle, its transid is useful.

Signed-off-by: Liu Bo <liubo2009@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 63f835a..8da29e8 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -337,8 +337,7 @@
 
 	if (num_bytes) {
 		trace_btrfs_space_reservation(root->fs_info, "transaction",
-					      (u64)(unsigned long)h,
-					      num_bytes, 1);
+					      h->transid, num_bytes, 1);
 		h->block_rsv = &root->fs_info->trans_block_rsv;
 		h->bytes_reserved = num_bytes;
 	}