vmm: api: Make FsConfig defaults match between CLI and HTTP API

In order to let the CLI and the HTTP API behave the same regarding the
FsConfig structure, this patch defines some default values for
num_queues, queue_size and the cache_size.

num_queues is set to 1, queue_size is set to 1024, and cache_size is set
to Some(8G) which means that DAX is enabled by default with a shared
region of 8GiB.

Fixes #508

Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>

vmm/src/api/openapi/cloud-hypervisor.yaml

@@ -312,8 +312,6 @@ components:
       required:
       - tag
       - sock
-      - num_queues
-      - queue_size
       type: object
       properties:
         tag:
@@ -322,11 +320,14 @@ components:
           type: string
         num_queues:
           type: integer
+          default: 1
         queue_size:
           type: integer
+          default: 1024
         cache_size:
           type: integer
           format: int64
+          default: 8589934592
 
     PmemConfig:
       required:

vmm/src/config.rs

@@ -427,11 +427,26 @@ impl Default for RngConfig {
 pub struct FsConfig {
     pub tag: String,
     pub sock: PathBuf,
+    #[serde(default = "default_fsconfig_num_queues")]
     pub num_queues: usize,
+    #[serde(default = "default_fsconfig_queue_size")]
     pub queue_size: u16,
+    #[serde(default = "default_fsconfig_cache_size")]
     pub cache_size: Option<u64>,
 }
 
+fn default_fsconfig_num_queues() -> usize {
+    1
+}
+
+fn default_fsconfig_queue_size() -> u16 {
+    1024
+}
+
+fn default_fsconfig_cache_size() -> Option<u64> {
+    Some(0x0002_0000_0000)
+}
+
 impl FsConfig {
     pub fn parse(fs: &str) -> Result<Self> {
         // Split the parameters based on the comma delimiter
@@ -460,11 +475,11 @@ impl FsConfig {
             }
         }
 
-        let mut num_queues: usize = 1;
+        let mut num_queues: usize = default_fsconfig_num_queues();
-        let mut queue_size: u16 = 1024;
+        let mut queue_size: u16 = default_fsconfig_queue_size();
         let mut dax: bool = true;
         // Default cache size set to 8Gib.
-        let mut cache_size: Option<u64> = Some(0x0002_0000_0000);
+        let mut cache_size: Option<u64> = default_fsconfig_cache_size();
 
         if tag.is_empty() {
             return Err(Error::ParseFsTagParam);