Re: [Qemu-devel] [PATCH 3/7] qcow2: add a migration blocker

[Lucas Meneghel Rodrigues]

On 11/12/2011 01:57 PM, Anthony Liguori wrote:
Now when you try to migrate with qcow2, you get:
(qemu) migrate tcp:localhost:1025
Block format 'qcow2' used by device 'ide0-hd0' does not support feature 'live 
migration'
(qemu)

LGTM. From a testing perspective, it's clear and understandable, a lot 
better than throwing a generic error.

Signed-off-by: Anthony Liguori<aligu...@us.ibm.com>
---
  block/qcow2.c |    9 +++++++++
  block/qcow2.h |    2 ++
  qemu-tool.c   |    9 +++++++++
  qerror.c      |    4 ++++
  qerror.h      |    3 +++
  5 files changed, 27 insertions(+), 0 deletions(-)

diff --git a/block/qcow2.c b/block/qcow2.c
index 5c784ee..e4126b7 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -29,6 +29,7 @@
  #include "block/qcow2.h"
  #include "qemu-error.h"
  #include "qerror.h"
+#include "migration.h"

  /*
    Differences with QCOW:
@@ -277,6 +278,11 @@ static int qcow2_open(BlockDriverState *bs, int flags)
          goto fail;
      }

+    error_set(&s->migration_blocker,
+              QERR_BLOCK_FORMAT_FEATURE_NOT_SUPPORTED,
+              "qcow2", bs->device_name, "live migration");
+    migrate_add_blocker(s->migration_blocker);
+
      /* Initialise locks */
      qemu_co_mutex_init(&s->lock);

@@ -621,6 +627,9 @@ static void qcow2_close(BlockDriverState *bs)
      BDRVQcowState *s = bs->opaque;
      g_free(s->l1_table);

+    migrate_del_blocker(s->migration_blocker);
+    error_free(s->migration_blocker);
+
      qcow2_cache_flush(bs, s->l2_table_cache);
      qcow2_cache_flush(bs, s->refcount_block_cache);

diff --git a/block/qcow2.h b/block/qcow2.h
index 531af39..0734b23 100644
--- a/block/qcow2.h
+++ b/block/qcow2.h
@@ -125,6 +125,8 @@ typedef struct BDRVQcowState {
      int snapshots_size;
      int nb_snapshots;
      QCowSnapshot *snapshots;
+
+    Error *migration_blocker;
  } BDRVQcowState;

  /* XXX: use std qcow open function ? */
diff --git a/qemu-tool.c b/qemu-tool.c
index e9f7fe1..5df7279 100644
--- a/qemu-tool.c
+++ b/qemu-tool.c
@@ -15,6 +15,7 @@
  #include "monitor.h"
  #include "qemu-timer.h"
  #include "qemu-log.h"
+#include "migration.h"

  #include<sys/time.h>

@@ -92,3 +93,11 @@ int64_t qemu_get_clock_ns(QEMUClock *clock)
  {
      return 0;
  }
+
+void migrate_add_blocker(Error *reason)
+{
+}
+
+void migrate_del_blocker(Error *reason)
+{
+}
diff --git a/qerror.c b/qerror.c
index 8e30e2d..fdf62b9 100644
--- a/qerror.c
+++ b/qerror.c
@@ -49,6 +49,10 @@ static const QErrorStringTable qerror_table[] = {
          .desc      = "Device '%(device)' can't go on a %(bad_bus_type) bus",
      },
      {
+        .error_fmt = QERR_BLOCK_FORMAT_FEATURE_NOT_SUPPORTED,
+        .desc      = "Block format '%(format)' used by device '%(name)' does not 
support feature '%(feature)'",
+    },
+    {
          .error_fmt = QERR_BUS_NOT_FOUND,
          .desc      = "Bus '%(bus)' not found",
      },
diff --git a/qerror.h b/qerror.h
index 7e2eebf..2d3d43b 100644
--- a/qerror.h
+++ b/qerror.h
@@ -54,6 +54,9 @@ QError *qobject_to_qerror(const QObject *obj);
  #define QERR_BAD_BUS_FOR_DEVICE \
      "{ 'class': 'BadBusForDevice', 'data': { 'device': %s, 'bad_bus_type': %s } 
}"

+#define QERR_BLOCK_FORMAT_FEATURE_NOT_SUPPORTED \
+    "{ 'class': 'BlockFormatFeatureNotSupported', 'data': { 'format': %s, 'name': 
%s, 'feature': %s } }"
+
  #define QERR_BUS_NOT_FOUND \
      "{ 'class': 'BusNotFound', 'data': { 'bus': %s } }"