feat(filesystem): 引入Umount系统调用 (#719)

* feat(filesystem): 引入Umount系统调用

* 将所有ENOSYS误用更正

* 修复了一个使同一个挂载点可以挂载2个文件系统的bug

* 统一注释，增强程序稳定性，统一接口。注意：Umount时在fatfs的路径要使用大写，此受限于当前文件系统设计。

kernel/src/arch/x86_64/kvm/mod.rs

@@ -34,14 +34,14 @@ impl X86_64KVMArch {
         // Check to see if CPU is Intel (“GenuineIntel”).
         if let Some(vi) = cpuid.get_vendor_info() {
             if vi.as_str() != "GenuineIntel" {
-                return Err(SystemError::EOPNOTSUPP_OR_ENOTSUP);
+                return Err(SystemError::ENOSYS);
             }
         }
         // Check processor supports for Virtual Machine Extension (VMX) technology
         // CPUID.1:ECX.VMX[bit 5] = 1 (Intel Manual: 24.6 Discovering Support for VMX)
         if let Some(fi) = cpuid.get_feature_info() {
             if !fi.has_vmx() {
-                return Err(SystemError::EOPNOTSUPP_OR_ENOTSUP);
+                return Err(SystemError::ENOSYS);
             }
         }
         Ok(())

kernel/src/arch/x86_64/kvm/vmx/ept.rs

@@ -15,7 +15,7 @@ pub fn check_ept_features() -> Result<(), SystemError> {
     const MTRR_ENABLE_BIT: u64 = 1 << 11;
     let ia32_mtrr_def_type = unsafe { msr::rdmsr(msr::IA32_MTRR_DEF_TYPE) };
     if (ia32_mtrr_def_type & MTRR_ENABLE_BIT) == 0 {
-        return Err(SystemError::EOPNOTSUPP_OR_ENOTSUP);
+        return Err(SystemError::ENOSYS);
     }
     Ok(())
 }

kernel/src/arch/x86_64/kvm/vmx/vcpu.rs

@@ -419,7 +419,7 @@ impl Vcpu for VmxVcpu {
             }
             Err(e) => {
                 kdebug!("[-] CPU does not support Intel VMX: {:?}", e);
-                return Err(SystemError::EOPNOTSUPP_OR_ENOTSUP);
+                return Err(SystemError::ENOSYS);
             }
         };
 
@@ -429,7 +429,7 @@ impl Vcpu for VmxVcpu {
             }
             Err(_) => {
                 kdebug!("[-] VMX operation is not supported on this processor.");
-                return Err(SystemError::EOPNOTSUPP_OR_ENOTSUP);
+                return Err(SystemError::ENOSYS);
             }
         }
 
@@ -574,12 +574,12 @@ pub fn has_intel_vmx_support() -> Result<(), SystemError> {
     let cpuid = CpuId::new();
     if let Some(vi) = cpuid.get_vendor_info() {
         if vi.as_str() != "GenuineIntel" {
-            return Err(SystemError::EOPNOTSUPP_OR_ENOTSUP);
+            return Err(SystemError::ENOSYS);
         }
     }
     if let Some(fi) = cpuid.get_feature_info() {
         if !fi.has_vmx() {
-            return Err(SystemError::EOPNOTSUPP_OR_ENOTSUP);
+            return Err(SystemError::ENOSYS);
         }
     }
     Ok(())