For malloc may fail, we should check it before assign
values to the fields of struct btrfs_trans_handle *h.

Signed-off-by: Wang Sheng-Hui <redacted>
---
 transaction.h |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/transaction.h b/transaction.h
index a1070e0..d4e42a1 100644
--- a/transaction.h
+++ b/transaction.h

@@ -32,7 +32,12 @@ static inline struct btrfs_trans_handle *
 btrfs_start_transaction(struct btrfs_root *root, int num_blocks)
 {
 	struct btrfs_fs_info *fs_info = root->fs_info;
+
 	struct btrfs_trans_handle *h = malloc(sizeof(*h));
+	if (!h) {
+		BUG();
+		return NULL;
+	}