[thin_shrink] add --no-copy

src/bin/thin_shrink.rs

@@ -33,6 +33,14 @@ fn main() {
                 .value_name("DATA")
                 .takes_value(true),
         )
+        .arg(
+            Arg::with_name("NOCOPY")
+                .help("Skip the copying of data, useful for benchmarking")
+                .required(false)
+                .long("no-copy")
+                .value_name("NOCOPY")
+                .takes_value(false),
+        )
         .arg(
             Arg::with_name("SIZE")
                 .help("Specify new size for the pool (in data blocks)")
@@ -49,13 +57,14 @@ fn main() {
     let output_file = matches.value_of("OUTPUT").unwrap();
     let size = matches.value_of("SIZE").unwrap().parse::<u64>().unwrap();
     let data_file = matches.value_of("DATA").unwrap();
+    let do_copy = !matches.is_present("NOCOPY");
 
     if !file_utils::file_exists(input_file) {
         eprintln!("Couldn't find input file '{}'.", &input_file);
         exit(1);
     }
 
-    if let Err(reason) = thinp::shrink::toplevel::shrink(&input_file, &output_file, &data_file, size) {
+    if let Err(reason) = thinp::shrink::toplevel::shrink(&input_file, &output_file, &data_file, size, do_copy) {
         println!("Application error: {}\n", reason);
         exit(1);
     }

src/shrink/toplevel.rs

@@ -433,7 +433,7 @@ fn process_xml<MV: xml::MetadataVisitor>(input_path: &str, pass: &mut MV) -> Res
     Ok(())
 }
 
-pub fn shrink(input_path: &str, output_path: &str, data_path: &str, nr_blocks: u64) -> Result<()> {
+pub fn shrink(input_path: &str, output_path: &str, data_path: &str, nr_blocks: u64, do_copy: bool) -> Result<()> {
     let mut pass1 = Pass1::new(nr_blocks);
     eprint!("Reading xml...");
     process_xml(input_path, &mut pass1)?;
@@ -454,8 +454,12 @@ pub fn shrink(input_path: &str, output_path: &str, data_path: &str, nr_blocks: u
 
     let remaps = build_remaps(above, free);
 
+    if do_copy {
         let regions = build_copy_regions(&remaps, pass1.block_size.unwrap() as u64);
         copier::copy(data_path, &regions)?;
+    } else {
+        eprintln!("skipping copy");
+    }
 
     let output = OpenOptions::new()
         .read(false)