ceph_test_rados: fix snap remove vs rollback fix

In commit 55d279b98553ba4542219b126fc7159b20b18b1f we tried to fix a race
between rollback and snap removal, but got the logic wrong: we need to
prevent *snap removal* on in-use snaps, not prevent multiple rollbacks on
the same snap.

Fixes: #6254 (again)
Signed-off-by: Sage Weil <sage@inktank.com>
Reviewed-by: Samuel Just <sam.just@inktank.com>

1 files changed, 7 insertions, 6 deletions

diff --git a/src/test/osd/TestRados.cc b/src/test/osd/TestRados.cc
index 7158f50a74a..842f9d2bca3 100644
--- a/src/test/osd/TestRados.cc
+++ b/src/test/osd/TestRados.cc
@@ -111,22 +111,23 @@ private:
       return new SnapCreateOp(m_op, &context, m_stats);
 
     case TEST_OP_SNAP_REMOVE:
-      if (context.snaps.empty()) {
+      if (context.snaps.size() <= context.snaps_in_use.size()) {
 	return NULL;
-      } else {
+      }
+      while (true) {
 	int snap = rand_choose(context.snaps)->first;
+	if (context.snaps_in_use.count(snap))
+	  continue;  // in use; try again!
 	cout << "snap_remove snap " << snap << std::endl;
 	return new SnapRemoveOp(m_op, &context, snap, m_stats);
       }
 
     case TEST_OP_ROLLBACK:
-      if (context.snaps.size() <= context.snaps_in_use.size()) {
+      if (context.snaps.empty()) {
 	return NULL;
       }
-      while (true) {
+      {
 	int snap = rand_choose(context.snaps)->first;
-	if (context.snaps_in_use.count(snap))
-	  continue;  // in use; try again!
 	string oid = *(rand_choose(context.oid_not_in_use));
 	cout << "rollback oid " << oid << " to " << snap << std::endl;
 	return new RollbackOp(m_op, &context, oid, snap);