main: replace block writable option with read_only

This is more consistent with the way it will be used in the virtio-blk
device model.

BUG=chromium:872973
TEST=cargo test

Change-Id: I28c5d007a7f3864ef6e18e9b343d263123302484
Signed-off-by: Daniel Verkamp <dverkamp@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/1170304
Reviewed-by: Dylan Reid <dgreid@chromium.org>
Reviewed-by: Zach Reizner <zachr@chromium.org>

src/linux.rs

@@ -405,15 +405,15 @@ fn setup_mmio_bus(cfg: &Config,
         } else {
             OpenOptions::new()
                 .read(true)
-                .write(disk.writable)
+                .write(!disk.read_only)
                 .open(&disk.path)
                 .map_err(|e| Error::Disk(e))?
         };
         // Lock the disk image to prevent other crosvm instances from using it.
-        let lock_op = if disk.writable {
+        let lock_op = if disk.read_only {
-            FlockOperation::LockExclusive
-        } else {
             FlockOperation::LockShared
+        } else {
+            FlockOperation::LockExclusive
         };
         flock(&raw_image, lock_op, true).map_err(Error::DiskImageLock)?;
 

src/main.rs

@@ -62,7 +62,7 @@ enum DiskType {
 
 struct DiskOption {
     path: PathBuf,
-    writable: bool,
+    read_only: bool,
     disk_type: DiskType,
 }
 
@@ -216,7 +216,7 @@ fn set_argument(cfg: &mut Config, name: &str, value: Option<&str>) -> argument::
             cfg.disks
                 .push(DiskOption {
                           path: disk_path,
-                          writable: name.starts_with("rw"),
+                          read_only: !name.starts_with("rw"),
                           disk_type: if name.ends_with("qcow") {
                                   DiskType::Qcow
                               } else {