[12/16] migration: Unwrap qemu_savevm_state_complete_precopy() in postcopy

Commit Message

Peter Xu Jan. 14, 2025, 11:07 p.m. UTC

Postcopy invokes qemu_savevm_state_complete_precopy() twice for a long
time, and that caused way too much confusions.  Let's clean this up and
make postcopy easier to read.

It's actually fairly straightforward: postcopy starts with saving
non-postcopiable iterables, then later it saves again with non-iterable
only.  Move these two calls out makes everything much easier to follow.
Otherwise it's very unclear what qemu_savevm_state_complete_precopy() did
in either of the calls.

No functional change intended.

Signed-off-by: Peter Xu <[e-mail]>
---
 migration/savevm.h    |  1 +
 migration/migration.c | 13 +++++++++++--
 migration/savevm.c    |  1 -
 3 files changed, 12 insertions(+), 3 deletions(-)

Patch

diff --git a/migration/savevm.h b/migration/savevm.h
index c48a53e95e..7957460062 100644
--- a/migration/savevm.h
+++ b/migration/savevm.h
@@ -44,6 +44,7 @@  void qemu_savevm_state_pending_exact(uint64_t *must_precopy,
                                      uint64_t *can_postcopy);
 void qemu_savevm_state_pending_estimate(uint64_t *must_precopy,
                                         uint64_t *can_postcopy);
+int qemu_savevm_state_complete_precopy_iterable(QEMUFile *f, bool in_postcopy);
 void qemu_savevm_send_ping(QEMUFile *f, uint32_t value);
 void qemu_savevm_send_open_return_path(QEMUFile *f);
 int qemu_savevm_send_packaged(QEMUFile *f, const uint8_t *buf, size_t len);
diff --git a/migration/migration.c b/migration/migration.c
index 2c5674c2ae..a8fe423a2b 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -2566,7 +2566,11 @@  static int postcopy_start(MigrationState *ms, Error **errp)
      * Cause any non-postcopiable, but iterative devices to
      * send out their final data.
      */
-    qemu_savevm_state_complete_precopy(ms->to_dst_file, true);
+    ret = qemu_savevm_state_complete_precopy_iterable(ms->to_dst_file, true);
+    if (ret) {
+        error_setg(errp, "Postcopy save non-postcopiable iterables failed");
+        goto fail;
+    }
 
     /*
      * in Finish migrate and with the io-lock held everything should
@@ -2605,7 +2609,12 @@  static int postcopy_start(MigrationState *ms, Error **errp)
      */
     qemu_savevm_send_postcopy_listen(fb);
 
-    qemu_savevm_state_complete_precopy(fb, false);
+    ret = qemu_savevm_state_complete_precopy_non_iterable(fb, true);
+    if (ret) {
+        error_setg(errp, "Postcopy save non-iterable device states failed");
+        goto fail_closefb;
+    }
+
     if (migrate_postcopy_ram()) {
         qemu_savevm_send_ping(fb, 3);
     }
diff --git a/migration/savevm.c b/migration/savevm.c
index 9aef2fa3c9..0ddc4c8eb5 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -1477,7 +1477,6 @@  void qemu_savevm_state_complete_postcopy(QEMUFile *f)
     qemu_fflush(f);
 }
 
-static
 int qemu_savevm_state_complete_precopy_iterable(QEMUFile *f, bool in_postcopy)
 {
     int64_t start_ts_each, end_ts_each;