CP-52620: enable read-through cache on persistent leaf

Signed-off-by: Mark Syms <[email protected]>

Author: MarkSymsCtx

drivers/blktap2.py

@@ -1970,7 +1970,7 @@ def _setup_cache(self, session, sr_uuid, vdi_uuid, local_sr_uuid,
             blktap = Blktap.allocate()
             child_options = copy.deepcopy(options)
             child_options["rdonly"] = False
-            child_options["lcache"] = False
+            child_options["lcache"] = (not scratch_mode)
             child_options["existing_prt"] = prt_tapdisk.minor
             child_options["secondary"] = secondary
             child_options["standby"] = scratch_mode

mk/sm.spec.in

@@ -24,6 +24,7 @@ Requires: xenserver-multipath
 Requires: python3-bitarray
 Requires: python3-future
 Conflicts: kernel < 4.19.19-5.0.0
+Conflicts: blktap < 3.55.3
 
 %description
 This package contains storage backends used in XCP