[PATCH v2 05/11] migration: Deliver return path file error to migrate state too

[Peter Xu <peterx@redhat.com>]

We've already did this for most of the return path thread errors, but not
yet for the IO errors happened on the return path qemufile.  Do that too.

Remember to reset "err" always, because the ownership is not us anymore,
otherwise we're prone to use-after-free later after recovered.

Re-export qemu_file_get_error_obj().

Reviewed-by: Fabiano Rosas <farosas@suse.de>
Signed-off-by: Peter Xu <peterx@redhat.com>
---
 migration/qemu-file.h | 1 +
 migration/migration.c | 7 +++++++
 migration/qemu-file.c | 2 +-
 3 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/migration/qemu-file.h b/migration/qemu-file.h
index 47015f5201..bc6edc5c39 100644
--- a/migration/qemu-file.h
+++ b/migration/qemu-file.h
@@ -129,6 +129,7 @@ void qemu_file_skip(QEMUFile *f, int size);
 void qemu_file_credit_transfer(QEMUFile *f, size_t size);
 int qemu_file_get_error_obj_any(QEMUFile *f1, QEMUFile *f2, Error **errp);
 void qemu_file_set_error_obj(QEMUFile *f, int ret, Error *err);
+int qemu_file_get_error_obj(QEMUFile *f, Error **errp);
 void qemu_file_set_error(QEMUFile *f, int ret);
 int qemu_file_shutdown(QEMUFile *f);
 QEMUFile *qemu_file_get_return_path(QEMUFile *f);
diff --git a/migration/migration.c b/migration/migration.c
index 825d8a71d4..216d0e871f 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -2038,6 +2038,13 @@ out:
 
     res = qemu_file_get_error(rp);
     if (res) {
+        /* We have forwarded any error in "err" already, reuse "error" */
+        assert(err == NULL);
+        /* Try to deliver this file error to migration state */
+        qemu_file_get_error_obj(rp, &err);
+        migrate_set_error(ms, err);
+        err = NULL;
+
         if (res && migration_in_postcopy()) {
             /*
              * Maybe there is something we can do: it looks like a
diff --git a/migration/qemu-file.c b/migration/qemu-file.c
index 19c33c9985..eea7171192 100644
--- a/migration/qemu-file.c
+++ b/migration/qemu-file.c
@@ -146,7 +146,7 @@ void qemu_file_set_hooks(QEMUFile *f, const QEMUFileHooks *hooks)
  * is not 0.
  *
  */
-static int qemu_file_get_error_obj(QEMUFile *f, Error **errp)
+int qemu_file_get_error_obj(QEMUFile *f, Error **errp)
 {
     if (errp) {
         *errp = f->last_error_obj ? error_copy(f->last_error_obj) : NULL;
-- 
2.41.0