fstests: don't oom the box opening tmpfiles (take 2)

For the t_open_tmpfiles tests that run multiple jobs in parallel,
limit ourselves to half of file-max for all jobs combined,
so that we don't OOM the test machine.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Eryu Guan <guaneryu@gmail.com>
diff --git a/tests/generic/531 b/tests/generic/531
index 8ce4cc9..ea77eec 100755
--- a/tests/generic/531
+++ b/tests/generic/531
@@ -41,10 +41,10 @@
 # Try to load up all the CPUs, two threads per CPU.
 nr_cpus=$(( $(getconf _NPROCESSORS_ONLN) * 2 ))
 
-# Set ULIMIT_NOFILE to min(file-max / 2, 50000 files per LOAD_FACTOR)
+# Set ULIMIT_NOFILE to min(file-max / $nr_cpus / 2, 50000 files per LOAD_FACTOR)
 # so that this test doesn't take forever or OOM the box
 max_files=$((50000 * LOAD_FACTOR))
-max_allowable_files=$(( $(cat /proc/sys/fs/file-max) / 2 ))
+max_allowable_files=$(( $(cat /proc/sys/fs/file-max) / $nr_cpus / 2 ))
 test $max_allowable_files -gt 0 && test $max_files -gt $max_allowable_files && \
 	max_files=$max_allowable_files
 ulimit -n $max_files
diff --git a/tests/xfs/502 b/tests/xfs/502
index 0a7921a..1b747a1 100755
--- a/tests/xfs/502
+++ b/tests/xfs/502
@@ -43,10 +43,10 @@
 # Load up all the CPUs, two threads per CPU.
 nr_cpus=$(( $(getconf _NPROCESSORS_ONLN) * 2 ))
 
-# Set ULIMIT_NOFILE to min(file-max / 2, 30000 files per cpu per LOAD_FACTOR)
+# Set ULIMIT_NOFILE to min(file-max / $nr_cpus / 2, 30000 files per cpu per LOAD_FACTOR)
 # so that this test doesn't take forever or OOM the box
 max_files=$((30000 * LOAD_FACTOR))
-max_allowable_files=$(( $(cat /proc/sys/fs/file-max) / 2 ))
+max_allowable_files=$(( $(cat /proc/sys/fs/file-max) / $nr_cpus / 2 ))
 test $max_allowable_files -gt 0 && test $max_files -gt $max_allowable_files && \
 	max_files=$max_allowable_files
 ulimit -n $max_files