Support kernel 4.19, which added file_operations.fadvise

Author: geofft

build.rs

@@ -71,6 +71,9 @@ fn handle_kernel_version_cfg(bindings_path: &PathBuf) {
     if version >= kernel_version_code(4, 15, 0) {
         println!("cargo:rustc-cfg=kernel_4_15_0_or_greataer")
     }
+    if version >= kernel_version_code(4, 19, 0) {
+        println!("cargo:rustc-cfg=kernel_4_19_0_or_greataer")
+    }
 }
 
 fn main() {

src/chrdev.rs

@@ -157,6 +157,8 @@ impl FileOperationsVtable {
             copy_file_range: None,
             dedupe_file_range: None,
             fallocate: None,
+            #[cfg(kernel_4_19_0_or_greataer)]
+            fadvise: None,
             fasync: None,
             flock: None,
             flush: None,