[pseudo,04/34] test-parallel-ops: Add a parallel create/rename/link/chmod test

diff --git a/test/test-parallel-ops.sh b/test/test-parallel-ops.sh
new file mode 100755
index 0000000..2fccd30
--- /dev/null
+++ b/test/test-parallel-ops.sh
@@ -0,0 +1,53 @@ 
+#!/bin/bash
+#
+# SPDX-License-Identifier: LGPL-2.1-only
+#
+# Several clients create, rename, link, chmod and remove the same names in
+# one directory at once.  pseudo must not let one client's operation land in
+# the middle of another client's change to the same name, or the server
+# finds the database out of step with the filesystem.  It then logs an
+# "inode mismatch" or "path mismatch" error, and may abort a client.
+#
+# The temporary tree has to live below $PWD so that pseudo tracks it.
+
+tmpdir="$(mktemp -d -p "$PWD" parallel_ops_XXXXXX)"
+trap "rm -rf '$tmpdir'" EXIT TERM INT
+
+log="${PSEUDO_LOCALSTATEDIR:-$PWD/var/pseudo}/pseudo.log"
+mismatches() {
+    grep -c "mismatch" "$log" 2>/dev/null || true
+}
+before=$(mismatches)
+
+cd "$tmpdir" || exit 1
+: > target
+
+worker() {
+    for i in $(seq 50); do
+        echo "$1 $i" > "tmp.$1"            || echo "FAILED: create tmp.$1" >> failed
+        mv -f "tmp.$1" target              || echo "FAILED: mv tmp.$1 target" >> failed
+        chmod 640 target 2>/dev/null
+        chown 0:0 target 2>/dev/null
+        ln -sf target lnk                  || echo "FAILED: ln -sf target lnk" >> failed
+        mkdir dir 2>/dev/null; rmdir dir 2>/dev/null
+        mkfifo "f.$1" && mv -f "f.$1" fifo || echo "FAILED: mkfifo/mv f.$1" >> failed
+        ln -f target "hard.$1" 2>/dev/null && rm -f "hard.$1"
+    done
+}
+
+for w in 1 2 3 4; do
+    worker $w &
+done
+wait
+
+rc=0
+if [ -e failed ]; then
+    sort failed | uniq -c
+    rc=1
+fi
+after=$(mismatches)
+if [ "${after:-0}" -ne "${before:-0}" ]; then
+    echo "FAILED: $((after - before)) mismatch error(s) in $log"
+    rc=1
+fi
+exit $rc