devices: block: issue fsync when FlushTimer expires

The RequestType::Flush handler correctly uses fsync(), which issues an
fsync to the underlying disk image file.  However, the flush timer
(started on write and cancelled if a flush request is executed) was only
calling flush(), which is insufficient when the disk image is a raw file
- it just flushes in-memory buffers and does not issue an fsync.

BUG=None
TEST=Issue writes in crosvm; verify fsync in strace output

Change-Id: I1de8a35615031b5fdf5599dd6b49015d0b245c31
Signed-off-by: Daniel Verkamp <dverkamp@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/1632876
Tested-by: kokoro <noreply+kokoro@google.com>
Legacy-Commit-Queue: Commit Bot <commit-bot@chromium.org>
Reviewed-by: Dylan Reid <dgreid@chromium.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/devices/src/virtio/block.rs b/devices/src/virtio/block.rs
index b0b5c2f..17a5723 100644
--- a/devices/src/virtio/block.rs
+++ b/devices/src/virtio/block.rs
@@ -747,7 +747,7 @@ impl<T: DiskFile> Worker<T> {
             for event in events.iter_readable() {
                 match event.token() {
                     Token::FlushTimer => {
-                        if let Err(e) = self.disk_image.flush() {
+                        if let Err(e) = self.disk_image.fsync() {
                             error!("Failed to flush the disk: {}", e);
                             break 'poll;
                         }