[io_engine] Add Block::zeroed() constructor

Cargo.lock

@@ -671,6 +671,12 @@ version = "1.0.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "71d301d4193d031abdd79ff7e3dd721168a9572ef3fe51a1517aba235bd8f86e"
 
+[[package]]
+name = "safemem"
+version = "0.3.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ef703b7cb59335eae2eb93ceb664c0eb7ea6bf567079d843e09420219668e072"
+
 [[package]]
 name = "shared_child"
 version = "0.3.4"
@@ -798,6 +804,7 @@ dependencies = [
  "quickcheck",
  "quickcheck_macros",
  "rand",
+ "safemem",
  "tempfile",
  "termion",
  "thiserror",

Cargo.toml

@@ -27,6 +27,7 @@ num-derive = "0.3"
 num-traits = "0.2"
 quick-xml = "0.18"
 rand = "0.7"
+safemem = "0.3.3"
 tempfile = "3.1"
 threadpool = "1.8"
 thiserror = "1.0"

src/io_engine.rs

@@ -1,5 +1,6 @@
 use io_uring::opcode::{self, types};
 use io_uring::IoUring;
+use safemem::write_bytes;
 use std::alloc::{alloc, dealloc, Layout};
 use std::fs::File;
 use std::fs::OpenOptions;
@@ -32,6 +33,12 @@ impl Block {
         Block { loc, data: ptr }
     }
 
+    pub fn zeroed(loc: u64) -> Block {
+        let r = Self::new(loc);
+        write_bytes(r.get_data(), 0);
+        r
+    }
+
     pub fn get_data<'a>(&self) -> &'a mut [u8] {
         unsafe { std::slice::from_raw_parts_mut::<'a>(self.data, BLOCK_SIZE) }
     }

src/report.rs

@@ -95,6 +95,7 @@ impl Report {
 
 //------------------------------------------
 
+#[allow(dead_code)]
 struct PBInner {
     title: String,
     bar: ProgressBar,