Remove fadvise

This commit removes the use of FADV_DONTNEED, which also purges active
cached pages for other processes.

src/restic/backend/local/local.go

@@ -157,11 +157,6 @@ func writeToTempfile(tempdir string, p []byte) (filename string, err error) {
 		return "", errors.Wrap(err, "Syncn")
 	}
 
-	err = fs.ClearCache(tmpfile)
-	if err != nil {
-		return "", errors.Wrap(err, "ClearCache")
-	}
-
 	err = tmpfile.Close()
 	if err != nil {
 		return "", errors.Wrap(err, "Close")

src/restic/fs/file.go

@@ -125,6 +125,11 @@ func Create(name string) (*os.File, error) {
 	return os.Create(fixpath(name))
 }
 
+// Open opens a file for reading.
+func Open(name string) (File, error) {
+	return os.Open(fixpath(name))
+}
+
 // OpenFile is the generalized open call; most users will use Open
 // or Create instead.  It opens the named file with specified flag
 // (O_RDONLY etc.) and perm, (0666 etc.) if applicable.  If successful,

src/restic/fs/file_linux.go

@@ -1,59 +0,0 @@
-// +build linux,go1.4
-
-package fs
-
-import (
-	"os"
-	"syscall"
-
-	"restic/errors"
-
-	"golang.org/x/sys/unix"
-)
-
-// Open opens a file for reading, without updating the atime and without caching data on read.
-func Open(name string) (File, error) {
-	file, err := os.OpenFile(name, os.O_RDONLY|syscall.O_NOATIME, 0)
-	if os.IsPermission(errors.Cause(err)) {
-		file, err = os.OpenFile(name, os.O_RDONLY, 0)
-	}
-	return &nonCachingFile{File: file}, err
-}
-
-// nonCachingFile wraps an *os.File and calls fadvise() to instantly forget
-// data that has been read or written.
-type nonCachingFile struct {
-	*os.File
-	readOffset int64
-}
-
-func (f *nonCachingFile) Read(p []byte) (int, error) {
-	n, err := f.File.Read(p)
-
-	if n > 0 {
-		ferr := unix.Fadvise(int(f.File.Fd()), f.readOffset, int64(n), unix.FADV_DONTNEED)
-
-		f.readOffset += int64(n)
-
-		if err == nil {
-			err = ferr
-		}
-	}
-
-	return n, err
-}
-
-// ClearCache syncs and then removes the file's content from the OS cache.
-func ClearCache(file File) error {
-	f, ok := file.(*os.File)
-	if !ok {
-		panic("ClearCache called for file not *os.File")
-	}
-
-	err := f.Sync()
-	if err != nil {
-		return err
-	}
-
-	return unix.Fadvise(int(f.Fd()), 0, 0, unix.FADV_DONTNEED)
-}

src/restic/fs/file_nonlinux.go

@@ -1,15 +0,0 @@
-// +build !linux !go1.4
-
-package fs
-
-import "os"
-
-// Open opens a file for reading.
-func Open(name string) (File, error) {
-	return os.OpenFile(fixpath(name), os.O_RDONLY, 0)
-}
-
-// ClearCache syncs and then removes the file's content from the OS cache.
-func ClearCache(f File) error {
-	return nil
-}