[PATCH for-4.5 v20 10/12] xl/remus: add a cmdline switch to disable disk replication

[Yang Hongyang <yanghy@cn.fujitsu.com>]

Disk replication is enabled by default. This patch adds a cmdline
switch to 'xl remus' command to explicitly disable disk replication.
A new boolean field 'diskbuf' is added to the libxl_domain_remus_info
structure to represent this configuration option inside libxl.

Note: Disabling disk replication requires enabling unsafe mode.

Signed-off-by: Yang Hongyang <yanghy@cn.fujitsu.com>
Signed-off-by: Shriram Rajagopalan <rshriram@cs.ubc.ca>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
---
 docs/man/xl.pod.1           |  6 +++++-
 tools/libxl/libxl.c         | 12 ++++++++----
 tools/libxl/libxl_types.idl |  1 +
 tools/libxl/xl_cmdimpl.c    |  5 ++++-
 tools/libxl/xl_cmdtable.c   |  5 +++--
 5 files changed, 21 insertions(+), 8 deletions(-)

diff --git a/docs/man/xl.pod.1 b/docs/man/xl.pod.1
index 1f165ad..362e92f 100644
--- a/docs/man/xl.pod.1
+++ b/docs/man/xl.pod.1
@@ -436,7 +436,7 @@ Enable Remus HA for domain. By default B<xl> relies on ssh as a transport
 mechanism between the two hosts.
 
 N.B: Remus support in xl is still in experimental (proof-of-concept) phase.
-     There is no support for disk buffering at the moment.
+     Disk replication support is limited to DRBD disks.
 
 B<OPTIONS>
 
@@ -479,6 +479,10 @@ Generally useful for debugging. Requires enabling unsafe mode.
 
 Disable network output buffering. Requires enabling unsafe mode.
 
+=item B<-d>
+
+Disable disk replication. Requires enabling unsafe mode.
+
 =back
 
 =item B<pause> I<domain-id>
diff --git a/tools/libxl/libxl.c b/tools/libxl/libxl.c
index fa757c4..f72c79b 100644
--- a/tools/libxl/libxl.c
+++ b/tools/libxl/libxl.c
@@ -808,12 +808,14 @@ int libxl_domain_remus_start(libxl_ctx *ctx, libxl_domain_remus_info *info,
     libxl_defbool_setdefault(&info->blackhole, false);
     libxl_defbool_setdefault(&info->compression, true);
     libxl_defbool_setdefault(&info->netbuf, true);
+    libxl_defbool_setdefault(&info->diskbuf, true);
 
     if (!libxl_defbool_val(info->unsafe) &&
         (libxl_defbool_val(info->blackhole) ||
-         !libxl_defbool_val(info->netbuf))) {
-        LOG(ERROR, "Unsafe mode must be enabled to replicate to /dev/null and "
-                   "disable network buffering");
+         !libxl_defbool_val(info->netbuf) ||
+         !libxl_defbool_val(info->diskbuf))) {
+        LOG(ERROR, "Unsafe mode must be enabled to replicate to /dev/null,"
+                   "disable network buffering and disk replication");
         goto out;
     }
 
@@ -841,7 +843,9 @@ int libxl_domain_remus_start(libxl_ctx *ctx, libxl_domain_remus_info *info,
         }
         rds->device_kind_flags |= (1 << LIBXL__DEVICE_KIND_REMUS_NIC);
     }
-    rds->device_kind_flags |= (1 << LIBXL__DEVICE_KIND_REMUS_DISK);
+
+    if (libxl_defbool_val(info->diskbuf))
+        rds->device_kind_flags |= (1 << LIBXL__DEVICE_KIND_REMUS_DISK);
 
     rds->ao = ao;
     rds->egc = egc;
diff --git a/tools/libxl/libxl_types.idl b/tools/libxl/libxl_types.idl
index 53f7daa..36ebfa5 100644
--- a/tools/libxl/libxl_types.idl
+++ b/tools/libxl/libxl_types.idl
@@ -616,6 +616,7 @@ libxl_domain_remus_info = Struct("domain_remus_info",[
     ("compression",  libxl_defbool),
     ("netbuf",       libxl_defbool),
     ("netbufscript", string),
+    ("diskbuf",      libxl_defbool),
     ])
 
 libxl_event_type = Enumeration("event_type", [
diff --git a/tools/libxl/xl_cmdimpl.c b/tools/libxl/xl_cmdimpl.c
index 2b61f16..abc8887 100644
--- a/tools/libxl/xl_cmdimpl.c
+++ b/tools/libxl/xl_cmdimpl.c
@@ -7497,7 +7497,7 @@ int main_remus(int argc, char **argv)
     r_info.interval = 200;
     libxl_defbool_setdefault(&r_info.blackhole, false);
 
-    SWITCH_FOREACH_OPT(opt, "Fbuni:s:N:e", NULL, "remus", 2) {
+    SWITCH_FOREACH_OPT(opt, "Fbundi:s:N:e", NULL, "remus", 2) {
     case 'i':
         r_info.interval = atoi(optarg);
         break;
@@ -7516,6 +7516,9 @@ int main_remus(int argc, char **argv)
     case 'N':
         r_info.netbufscript = optarg;
         break;
+    case 'd':
+        libxl_defbool_set(&r_info.diskbuf, false);
+        break;
     case 's':
         ssh_command = optarg;
         break;
diff --git a/tools/libxl/xl_cmdtable.c b/tools/libxl/xl_cmdtable.c
index cd1b612..f93ee4f 100644
--- a/tools/libxl/xl_cmdtable.c
+++ b/tools/libxl/xl_cmdtable.c
@@ -503,11 +503,12 @@ struct cmd_spec cmd_table[] = {
       "                        of the domain.\n"
       "-N <netbufscript>       Use netbufscript to setup network buffering instead of the\n"
       "                        default script (/etc/xen/scripts/remus-netbuf-setup).\n"
-      "-F                      Enable unsafe configurations [-b|-n flags]. Use this option\n"
+      "-F                      Enable unsafe configurations [-b|-n|-d flags]. Use this option\n"
       "                        with caution as failover may not work as intended.\n"
       "-b                      Replicate memory checkpoints to /dev/null (blackhole).\n"
       "                        Works only in unsafe mode.\n"
-      "-n                      Disable network output buffering. Works only in unsafe mode."
+      "-n                      Disable network output buffering. Works only in unsafe mode.\n"
+      "-d                      Disable disk replication. Works only in unsafe mode."
     },
 #endif
     { "devd",
-- 
1.9.1