qemu-file: Make qemu_fflush() return errors

This let us simplify code of this shape.

   qemu_fflush(f);
   int ret = qemu_file_get_error(f);
   if (ret) {
      return ret;
   }

into:

   int ret = qemu_fflush(f);
   if (ret) {
      return ret;
   }

I updated all callers where there is any error check.
qemu_fclose() don't need to check for f->last_error because
qemu_fflush() returns it at the beggining of the function.

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Signed-off-by: Juan Quintela <quintela@redhat.com>

Message-ID: <20231025091117.6342-13-quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>

Author: Juan Quintela

migration/colo.c

@@ -314,9 +314,7 @@ static void colo_send_message(QEMUFile *f, COLOMessage msg,
         return;
     }
     qemu_put_be32(f, msg);
-    qemu_fflush(f);
-
-    ret = qemu_file_get_error(f);
+    ret = qemu_fflush(f);
     if (ret < 0) {
         error_setg_errno(errp, -ret, "Can't send COLO message");
     }
@@ -335,9 +333,7 @@ static void colo_send_message_value(QEMUFile *f, COLOMessage msg,
         return;
     }
     qemu_put_be64(f, value);
-    qemu_fflush(f);
-
-    ret = qemu_file_get_error(f);
+    ret = qemu_fflush(f);
     if (ret < 0) {
         error_setg_errno(errp, -ret, "Failed to send value for message:%s",
                          COLOMessage_str(msg));
@@ -483,8 +479,7 @@ static int colo_do_checkpoint_transaction(MigrationState *s,
     }
 
     qemu_put_buffer(s->to_dst_file, bioc->data, bioc->usage);
-    qemu_fflush(s->to_dst_file);
-    ret = qemu_file_get_error(s->to_dst_file);
+    ret = qemu_fflush(s->to_dst_file);
     if (ret < 0) {
         goto out;
     }

migration/migration.c

@@ -305,12 +305,7 @@ static int migrate_send_rp_message(MigrationIncomingState *mis,
     qemu_put_be16(mis->to_src_file, (unsigned int)message_type);
     qemu_put_be16(mis->to_src_file, len);
     qemu_put_buffer(mis->to_src_file, data, len);
-    qemu_fflush(mis->to_src_file);
-
-    /* It's possible that qemu file got error during sending */
-    ret = qemu_file_get_error(mis->to_src_file);
-
-    return ret;
+    return qemu_fflush(mis->to_src_file);
 }
 
 /* Request one page from the source VM at the given start address.

migration/qemu-file.c

@@ -262,14 +262,14 @@ static void qemu_iovec_release_ram(QEMUFile *f)
  * This will flush all pending data. If data was only partially flushed, it
  * will set an error state.
  */
-void qemu_fflush(QEMUFile *f)
+int qemu_fflush(QEMUFile *f)
 {
     if (!qemu_file_is_writable(f)) {
-        return;
+        return f->last_error;
     }
 
-    if (qemu_file_get_error(f)) {
-        return;
+    if (f->last_error) {
+        return f->last_error;
     }
     if (f->iovcnt > 0) {
         Error *local_error = NULL;
@@ -287,6 +287,7 @@ void qemu_fflush(QEMUFile *f)
 
     f->buf_index = 0;
     f->iovcnt = 0;
+    return f->last_error;
 }
 
 /*
@@ -353,22 +354,12 @@ static ssize_t coroutine_mixed_fn qemu_fill_buffer(QEMUFile *f)
  */
 int qemu_fclose(QEMUFile *f)
 {
-    int ret, ret2;
-    qemu_fflush(f);
-    ret = qemu_file_get_error(f);
-
-    ret2 = qio_channel_close(f->ioc, NULL);
+    int ret = qemu_fflush(f);
+    int ret2 = qio_channel_close(f->ioc, NULL);
     if (ret >= 0) {
         ret = ret2;
     }
     g_clear_pointer(&f->ioc, object_unref);
-
-    /* If any error was spotted before closing, we should report it
-     * instead of the close() return value.
-     */
-    if (f->last_error) {
-        ret = f->last_error;
-    }
     error_free(f->last_error_obj);
     g_free(f);
     trace_qemu_file_fclose();

migration/qemu-file.h

@@ -71,7 +71,7 @@ void qemu_file_set_error_obj(QEMUFile *f, int ret, Error *err);
 void qemu_file_set_error(QEMUFile *f, int ret);
 int qemu_file_shutdown(QEMUFile *f);
 QEMUFile *qemu_file_get_return_path(QEMUFile *f);
-void qemu_fflush(QEMUFile *f);
+int qemu_fflush(QEMUFile *f);
 void qemu_file_set_blocking(QEMUFile *f, bool block);
 int qemu_file_get_to_fd(QEMUFile *f, int fd, size_t size);
 

migration/ram.c

@@ -305,17 +305,15 @@ int64_t ramblock_recv_bitmap_send(QEMUFile *file,
 
     qemu_put_be64(file, size);
     qemu_put_buffer(file, (const uint8_t *)le_bitmap, size);
+    g_free(le_bitmap);
     /*
      * Mark as an end, in case the middle part is screwed up due to
      * some "mysterious" reason.
      */
     qemu_put_be64(file, RAMBLOCK_RECV_BITMAP_ENDING);
-    qemu_fflush(file);
-
-    g_free(le_bitmap);
-
-    if (qemu_file_get_error(file)) {
-        return qemu_file_get_error(file);
+    int ret = qemu_fflush(file);
+    if (ret) {
+        return ret;
     }
 
     return size + sizeof(size);
@@ -2996,9 +2994,7 @@ static int ram_save_setup(QEMUFile *f, void *opaque)
     }
 
     qemu_put_be64(f, RAM_SAVE_FLAG_EOS);
-    qemu_fflush(f);
-
-    return 0;
+    return qemu_fflush(f);
 }
 
 /**
@@ -3118,10 +3114,8 @@ static int ram_save_iterate(QEMUFile *f, void *opaque)
         }
 
         qemu_put_be64(f, RAM_SAVE_FLAG_EOS);
-        qemu_fflush(f);
         ram_transferred_add(8);
-
-        ret = qemu_file_get_error(f);
+        ret = qemu_fflush(f);
     }
     if (ret < 0) {
         return ret;
@@ -3196,9 +3190,7 @@ static int ram_save_complete(QEMUFile *f, void *opaque)
         qemu_put_be64(f, RAM_SAVE_FLAG_MULTIFD_FLUSH);
     }
     qemu_put_be64(f, RAM_SAVE_FLAG_EOS);
-    qemu_fflush(f);
-
-    return 0;
+    return qemu_fflush(f);
 }
 
 static void ram_state_pending_estimate(void *opaque, uint64_t *must_precopy,

migration/rdma.c

@@ -3853,9 +3853,7 @@ int rdma_registration_start(QEMUFile *f, uint64_t flags)
 
     trace_rdma_registration_start(flags);
     qemu_put_be64(f, RAM_SAVE_FLAG_HOOK);
-    qemu_fflush(f);
-
-    return 0;
+    return qemu_fflush(f);
 }
 
 /*

migration/savevm.c

@@ -1583,8 +1583,7 @@ int qemu_savevm_state_complete_precopy(QEMUFile *f, bool iterable_only,
     }
 
 flush:
-    qemu_fflush(f);
-    return 0;
+    return qemu_fflush(f);
 }
 
 /* Give an estimate of the amount left to be transferred,