virtio-blk: fix barrier support
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 <hch@lst.de>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
diff --git a/hw/virtio-blk.c b/hw/virtio-blk.c
index d270225..5d7f1a2 100644
--- a/hw/virtio-blk.c
+++ b/hw/virtio-blk.c
@@ -240,10 +240,20 @@
}
}
-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);
@@ -316,7 +326,8 @@
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) {
