[PATCH 5/4] generic/173: don't dump core when mwrite fails

["Darrick J. Wong" <darrick.wong@oracle.com>]

In generic/173, we try to force a CoW to a mmap'd region to fail if
there's no space to actually stage the CoW operation.  That failure
comes in the form of a SIGBUS to xfs_io.  If the tester just happens to
have a nonzero coresize ulimit set, a core dump is generated and the
test is marked as having failed, even though the dump generation is
exactly the correct behavior.

Therefore, set the coresize ulimit to zero while calling _mwrite_byte.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
 tests/generic/173 |    3 +++
 1 file changed, 3 insertions(+)

diff --git a/tests/generic/173 b/tests/generic/173
index ad4e5da..526590b 100755
--- a/tests/generic/173
+++ b/tests/generic/173
@@ -81,6 +81,8 @@ _fill_fs $((blksz * nr_free)) $testdir/space $blksz 0 >> $seqres.full 2>&1
 sync
 
 echo "mmap CoW the big file"
+core_ulimit="$(ulimit -c)"
+ulimit -c 0
 out="$(_mwrite_byte 0x62 0 $((blksz * nr_blks)) $((blksz * nr_blks)) $testdir/bigfile 2>&1)"
 err="$?"
 if [ $err -lt 128 ]; then
@@ -95,6 +97,7 @@ err="$?"
 if [ $err -lt 128 ]; then
 	echo "mmap CoW should have failed with SIGBUS, got SIG$(kill -l $err)"
 fi
+ulimit -c "${core_ulimit}"
 
 # success, all done
 status=0