Before issuing the barrier to the block driver we need to flush our oustanding
queue of write requests, as the flush is supposed to be issued after them.
Signed-off-by: Christoph Hellwig <h...@lst.de>
Index: qemu/hw/virtio-blk.c
===================================================================
--- qemu.orig/hw/virtio-blk.c 2010-05-19 11:05:23.259005741 +0200
+++ qemu/hw/virtio-blk.c 2010-05-19 11:08:09.797255846 +0200
@@ -238,10 +238,20 @@ static void do_multiwrite(BlockDriverSta
}
}
-static void virtio_blk_handle_flush(VirtIOBlockReq *req)
+static void virtio_blk_handle_flush(BlockRequest *blkreq, int *num_writes,
+ VirtIOBlockReq *req, BlockDriverState **old_bs)
{
BlockDriverAIOCB *acb;
+ /*
+ * Make sure all outstanding writes are posted to the backing device.
+ */
+ if (*old_bs != NULL) {
+ do_multiwrite(*old_bs, blkreq, *num_writes);
+ }
+ *num_writes = 0;
+ *old_bs = req->dev->bs;
+
acb = bdrv_aio_flush(req->dev->bs, virtio_blk_flush_complete, req);
if (!acb) {
virtio_blk_req_complete(req, VIRTIO_BLK_S_IOERR);
@@ -314,7 +324,8 @@ static void virtio_blk_handle_request(Vi
req->in = (void *)req->elem.in_sg[req->elem.in_num - 1].iov_base;
if (req->out->type & VIRTIO_BLK_T_FLUSH) {
- virtio_blk_handle_flush(req);
+ virtio_blk_handle_flush(mrb->blkreq, &mrb->num_writes,
+ req, &mrb->old_bs);
} else if (req->out->type & VIRTIO_BLK_T_SCSI_CMD) {
virtio_blk_handle_scsi(req);
} else if (req->out->type & VIRTIO_BLK_T_OUT) {
