devices: block: add option to control sparseness

Extend the --disk option and other related options to allow a particular
disk to have the sparse operations (virtio-blk's discard command)
enabled or disabled.

By default, the sparse flag will be enabled for virtio-blk devices,
matching current behavior.

BUG=chromium:858815
TEST=Run `crosvm with --rwdisk file.img,sparse=false` and try to discard

Change-Id: Ib72c949711fbe869a3f444d7f929a80d0e039f72
Signed-off-by: Daniel Verkamp <dverkamp@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosvm/+/1906750
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Zach Reizner <zachr@chromium.org>

1 files changed, 7 insertions, 2 deletions

diff --git a/src/linux.rs b/src/linux.rs
index 1177377..25aba0f 100644
--- a/src/linux.rs
+++ b/src/linux.rs
@@ -358,8 +358,13 @@ fn create_block_device(
     flock(&raw_image, lock_op, true).map_err(Error::DiskImageLock)?;
 
     let disk_file = disk::create_disk_file(raw_image).map_err(Error::CreateDiskError)?;
-    let dev = virtio::Block::new(disk_file, disk.read_only, Some(disk_device_socket))
-        .map_err(Error::BlockDeviceNew)?;
+    let dev = virtio::Block::new(
+        disk_file,
+        disk.read_only,
+        disk.sparse,
+        Some(disk_device_socket),
+    )
+    .map_err(Error::BlockDeviceNew)?;
 
     Ok(VirtioDeviceStub {
         dev: Box::new(dev),