qa: add 16MB direct-io write test

See bug #2657.

Signed-off-by: Sage Weil <sage@inktank.com>

diff --git a/qa/workunits/direct_io/big.sh b/qa/workunits/direct_io/big.sh
new file mode 100755 (executable)
index 0000000..43bd6d7
--- /dev/null
+++ b/qa/workunits/direct_io/big.sh
@@ -0,0 +1,6 @@
+#!/bin/sh -ex
+
+echo "test large (16MB) dio write"
+dd if=/dev/zero of=foo.big bs=16M count=1 oflag=direct
+
+echo OK