ext4: Use WRITE_SYNC for commits which are caused by fsync()

If a commit is triggered by fsync(), set a flag indicating the journal
blocks associated with the transaction should be flushed out using
WRITE_SYNC.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

include/linux/jbd2.h

@@ -648,6 +648,12 @@ struct transaction_s
 	 */
 	int t_handle_count;
 
+	/*
+	 * This transaction is being forced and some process is
+	 * waiting for it to finish.
+	 */
+	int t_synchronous_commit:1;
+
 	/*
 	 * For use by the filesystem to store fs-specific data
 	 * structures associated with the transaction