scoutfs-tests: add persistent-item-vers test

Add a test which makes sure that we don't initialize the lock server's
write version to a version less than existing log tree items.

Signed-off-by: Zach Brown <zab@versity.com>

tests/golden/persistent-item-vers

@@ -0,0 +1,4 @@
+== advance lock version by creating unrelated files
+== create before file version
+== verify before version, touch after version
+== verify after version

tests/sequence

@@ -19,6 +19,7 @@ dirent-consistency.sh
 lock-ex-race-processes.sh
 lock-conflicting-batch-commit.sh
 cross-mount-data-free.sh
+persistent-item-vers.sh
 setup-error-teardown.sh
 mount-unmount-race.sh
 createmany-parallel-mounts.sh

tests/tests/persistent-item-vers.sh

@@ -0,0 +1,45 @@
+#
+# make sure we increment item vers from persistent items
+#
+# Make sure that new locks are given a write_version that is greater
+# than all existing items so that new items with greater versions are
+# preferred over old versions with lesser versions.
+#
+# We create an inode in a mount that has been granted multiple locks,
+# which could lead to a greater version.  We then modify the item very
+# early in a mount so that it's lock could have a lesser version.
+#
+# This was all written to test a bug where the write_version was
+# statically initialized as the module was inserted.
+#
+
+t_require_commands mkdir createmany touch stat sleep diff
+
+echo "== advance lock version by creating unrelated files"
+mkdir "$T_D0/a"
+createmany -o "$T_D0/a/file-" 10240 2>&1 > /dev/null
+mkdir "$T_D0/b"
+createmany -o "$T_D0/b/file-" 10240 2>&1 > /dev/null
+
+echo "== create before file version"
+touch "$T_D0/file"
+stat "$T_D0/file" | grep Modify: > "$T_TMP.before"
+
+# remount, possibly wiping the lock server's write_version
+t_reinsert_remount_all
+
+echo "== verify before version, touch after version"
+stat "$T_D0/file" | grep Modify: > "$T_TMP.b"
+diff -u "$T_TMP.before" "$T_TMP.b"
+sleep 1
+touch "$T_D0/file"
+stat "$T_D0/file" | grep Modify: > "$T_TMP.after"
+
+# remount and make sure we got the newest version
+t_remount_all
+
+echo "== verify after version"
+stat "$T_D0/file" | grep Modify: > "$T_TMP.a"
+diff -u "$T_TMP.after" "$T_TMP.a"
+
+t_pass