Use copy file range from sysx

Use pooled buffers for copy

Signed-off-by: Derek McGowan <derek@mcgstyle.net> (github: dmcgowan)

fs/copy.go

@@ -4,10 +4,19 @@ import (
 	"io/ioutil"
 	"os"
 	"path/filepath"
+	"sync"
 
 	"github.com/pkg/errors"
 )
 
+var (
+	bufferPool = &sync.Pool{
+		New: func() interface{} {
+			return make([]byte, 32*1024)
+		},
+	}
+)
+
 // CopyDirectory copies the directory from src to dst.
 // Most efficient copy of files is attempted.
 func CopyDirectory(dst, src string) error {

fs/copy_linux.go

@@ -3,49 +3,12 @@ package fs
 import (
 	"io"
 	"os"
-	"strconv"
 	"syscall"
 
 	"github.com/pkg/errors"
 	"github.com/stevvooe/continuity/sysx"
 )
 
-var (
-	kernel, major int
-)
-
-func init() {
-	uts := &syscall.Utsname{}
-
-	err := syscall.Uname(uts)
-	if err != nil {
-		panic(err)
-	}
-
-	p := [2][]byte{{}, {}}
-
-	release := uts.Release
-	i := 0
-	for pi := 0; pi < len(p); pi++ {
-		for release[i] != 0 {
-			c := byte(release[i])
-			i++
-			if c == '.' || c == '-' {
-				break
-			}
-			p[pi] = append(p[pi], c)
-		}
-	}
-	kernel, err = strconv.Atoi(string(p[0]))
-	if err != nil {
-		panic(err)
-	}
-	major, err = strconv.Atoi(string(p[1]))
-	if err != nil {
-		panic(err)
-	}
-}
-
 func copyFileInfo(fi os.FileInfo, name string) error {
 	st := fi.Sys().(*syscall.Stat_t)
 	if err := os.Lchown(name, int(st.Uid), int(st.Gid)); err != nil {
@@ -66,29 +29,28 @@ func copyFileInfo(fi os.FileInfo, name string) error {
 }
 
 func copyFileContent(dst, src *os.File) error {
-	if checkKernel(4, 5) {
-		// Use copy_file_range to do in kernel copying
-		// See https://lwn.net/Articles/659523/
-		// 326 on x86_64
-		st, err := src.Stat()
-		if err != nil {
-			return errors.Wrap(err, "unable to stat source")
-		}
-		n, _, e1 := syscall.Syscall6(326, src.Fd(), 0, dst.Fd(), 0, uintptr(st.Size()), 0)
-		if e1 != 0 {
-			return errors.Wrap(err, "copy_file_range failed")
-		}
-		if int64(n) != st.Size() {
-			return errors.Wrapf(err, "short copy: %d of %d", int64(n), st.Size())
-		}
-		return nil
+	st, err := src.Stat()
+	if err != nil {
+		return errors.Wrap(err, "unable to stat source")
 	}
-	_, err := io.Copy(dst, src)
-	return err
-}
 
-func checkKernel(k, m int) bool {
-	return (kernel == k && major >= m) || kernel > k
+	n, err := sysx.CopyFileRange(src.Fd(), nil, dst.Fd(), nil, int(st.Size()), 0)
+	if err != nil {
+		if err != syscall.ENOSYS && err != syscall.EXDEV {
+			return errors.Wrap(err, "copy file range failed")
+		}
+
+		buf := bufferPool.Get().([]byte)
+		_, err = io.CopyBuffer(dst, src, buf)
+		bufferPool.Put(buf)
+		return err
+	}
+
+	if int64(n) != st.Size() {
+		return errors.Wrapf(err, "short copy: %d of %d", int64(n), st.Size())
+	}
+
+	return nil
 }
 
 func copyXAttrs(dst, src string) error {

fs/copy_windows.go

@@ -18,7 +18,9 @@ func copyFileInfo(fi os.FileInfo, name string) error {
 }
 
 func copyFileContent(dst, src *os.File) error {
-	_, err := io.Copy(dst, src)
+	buf := bufferPool.Get().([]byte)
+	_, err := io.CopyBuffer(dst, src, buf)
+	bufferPool.Put(buf)
 	return err
 }