diff --git a/extent-tree.c b/extent-tree.c
index 8c9cdeff..283a6917 100644
--- a/extent-tree.c
+++ b/extent-tree.c
@@ -2506,7 +2506,12 @@ int btrfs_reserve_extent(struct btrfs_trans_handle *trans,
 		profile = BTRFS_BLOCK_GROUP_METADATA | alloc_profile;
 	}
 
-	if (root->ref_cows) {
+	/*
+	 * Do metadata preallocation if we're not modifying the extent tree.
+	 * Allocating chunk while modifying extent tree could lead to transid
+	 * mismatch, as do_chunk_alloc() could commit transaction.
+	 */
+	if (root->root_key.objectid != BTRFS_EXTENT_TREE_OBJECTID) {
 		if (!(profile & BTRFS_BLOCK_GROUP_METADATA)) {
 			ret = do_chunk_alloc(trans, info,
 					     num_bytes,