[Qemu-devel] [PATCH 2/6] Split header writing out of qemu_savevm_state_begin

["Dr. David Alan Gilbert (git)" <dgilbert@redhat.com>]

From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>

Split qemu_savevm_state_begin to:
  qemu_savevm_state_header   That writes the initial file header.
  qemu_savevm_state_begin    That sets up devices and does the first
                             device pass.

Used later in postcopy.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Amit Shah <amit.shah@redhat.com>
---
 include/sysemu/sysemu.h |  1 +
 migration/migration.c   |  1 +
 savevm.c                | 11 ++++++++---
 trace-events            |  1 +
 4 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/include/sysemu/sysemu.h b/include/sysemu/sysemu.h
index 8a52934..7a1ea91 100644
--- a/include/sysemu/sysemu.h
+++ b/include/sysemu/sysemu.h
@@ -84,6 +84,7 @@ void qemu_announce_self(void);
 bool qemu_savevm_state_blocked(Error **errp);
 void qemu_savevm_state_begin(QEMUFile *f,
                              const MigrationParams *params);
+void qemu_savevm_state_header(QEMUFile *f);
 int qemu_savevm_state_iterate(QEMUFile *f);
 void qemu_savevm_state_complete(QEMUFile *f);
 void qemu_savevm_state_cancel(void);
diff --git a/migration/migration.c b/migration/migration.c
index 732d229..1660d74 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -738,6 +738,7 @@ static void *migration_thread(void *opaque)
     int64_t start_time = initial_time;
     bool old_vm_running = false;
 
+    qemu_savevm_state_header(s->file);
     qemu_savevm_state_begin(s->file, &s->params);
 
     s->setup_time = qemu_clock_get_ms(QEMU_CLOCK_HOST) - setup_start;
diff --git a/savevm.c b/savevm.c
index c162dfd..d9f0cca 100644
--- a/savevm.c
+++ b/savevm.c
@@ -616,6 +616,13 @@ bool qemu_savevm_state_blocked(Error **errp)
     return false;
 }
 
+void qemu_savevm_state_header(QEMUFile *f)
+{
+    trace_savevm_state_header();
+    qemu_put_be32(f, QEMU_VM_FILE_MAGIC);
+    qemu_put_be32(f, QEMU_VM_FILE_VERSION);
+}
+
 void qemu_savevm_state_begin(QEMUFile *f,
                              const MigrationParams *params)
 {
@@ -630,9 +637,6 @@ void qemu_savevm_state_begin(QEMUFile *f,
         se->ops->set_params(params, se->opaque);
     }
 
-    qemu_put_be32(f, QEMU_VM_FILE_MAGIC);
-    qemu_put_be32(f, QEMU_VM_FILE_VERSION);
-
     QTAILQ_FOREACH(se, &savevm_handlers, entry) {
         int len;
 
@@ -842,6 +846,7 @@ static int qemu_savevm_state(QEMUFile *f, Error **errp)
     }
 
     qemu_mutex_unlock_iothread();
+    qemu_savevm_state_header(f);
     qemu_savevm_state_begin(f, &params);
     qemu_mutex_lock_iothread();
 
diff --git a/trace-events b/trace-events
index 11387c3..30bcd64 100644
--- a/trace-events
+++ b/trace-events
@@ -1174,6 +1174,7 @@ qemu_loadvm_state_section_startfull(uint32_t section_id, const char *idstr, uint
 savevm_section_start(const char *id, unsigned int section_id) "%s, section_id %u"
 savevm_section_end(const char *id, unsigned int section_id, int ret) "%s, section_id %u -> %d"
 savevm_state_begin(void) ""
+savevm_state_header(void) ""
 savevm_state_iterate(void) ""
 savevm_state_complete(void) ""
 savevm_state_cancel(void) ""
-- 
2.4.1