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Fix copying hardlinks in graphdriver/copy

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Previously, graphdriver/copy would improperly copy hardlinks as just regular
files. This patch changes that behaviour, and instead the code now keeps
track of inode numbers, and if it sees the same inode number again
during the copy loop, it hardlinks it, instead of copying it.

Signed-off-by: Sargun Dhillon <sargun@sargun.me>
This commit is contained in:
Sargun Dhillon 2017-11-21 10:11:43 -08:00
parent c307e0ce49
commit b467f8b2ef
2 changed files with 45 additions and 0 deletions
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14
daemon/graphdriver/copy/copy.go
View file

@ -106,11 +106,19 @@ func copyXattr(srcPath, dstPath, attr string) error {
return nil return nil
} }
type fileID struct {
dev uint64
ino uint64
}
// DirCopy copies or hardlinks the contents of one directory to another, // DirCopy copies or hardlinks the contents of one directory to another,
// properly handling xattrs, and soft links // properly handling xattrs, and soft links
func DirCopy(srcDir, dstDir string, copyMode Mode) error { func DirCopy(srcDir, dstDir string, copyMode Mode) error {
copyWithFileRange := true copyWithFileRange := true
copyWithFileClone := true copyWithFileClone := true
// This is a map of source file inodes to dst file paths
copiedFiles := make(map[fileID]string)
err := filepath.Walk(srcDir, func(srcPath string, f os.FileInfo, err error) error { err := filepath.Walk(srcDir, func(srcPath string, f os.FileInfo, err error) error {
if err != nil { if err != nil {
return err return err
@ -136,15 +144,21 @@ func DirCopy(srcDir, dstDir string, copyMode Mode) error {
switch f.Mode() & os.ModeType { switch f.Mode() & os.ModeType {
case 0: // Regular file case 0: // Regular file
id := fileID{dev: stat.Dev, ino: stat.Ino}
if copyMode == Hardlink { if copyMode == Hardlink {
isHardlink = true isHardlink = true
if err2 := os.Link(srcPath, dstPath); err2 != nil { if err2 := os.Link(srcPath, dstPath); err2 != nil {
return err2 return err2
} }
} else if hardLinkDstPath, ok := copiedFiles[id]; ok {
if err2 := os.Link(hardLinkDstPath, dstPath); err2 != nil {
return err2
}
} else { } else {
if err2 := copyRegular(srcPath, dstPath, f, &copyWithFileRange, &copyWithFileClone); err2 != nil { if err2 := copyRegular(srcPath, dstPath, f, &copyWithFileRange, &copyWithFileClone); err2 != nil {
return err2 return err2
} }
copiedFiles[id] = dstPath
} }
case os.ModeDir: case os.ModeDir:

31
daemon/graphdriver/copy/copy_test.go
View file

@ -9,6 +9,8 @@ import (
"path/filepath" "path/filepath"
"testing" "testing"
"golang.org/x/sys/unix"
"github.com/docker/docker/pkg/parsers/kernel" "github.com/docker/docker/pkg/parsers/kernel"
"github.com/stretchr/testify/assert" "github.com/stretchr/testify/assert"
"github.com/stretchr/testify/require" "github.com/stretchr/testify/require"
@ -65,3 +67,32 @@ func doCopyTest(t *testing.T, copyWithFileRange, copyWithFileClone *bool) {
require.NoError(t, err) require.NoError(t, err)
assert.Equal(t, buf, readBuf) assert.Equal(t, buf, readBuf)
} }
func TestCopyHardlink(t *testing.T) {
var srcFile1FileInfo, srcFile2FileInfo, dstFile1FileInfo, dstFile2FileInfo unix.Stat_t
srcDir, err := ioutil.TempDir("", "srcDir")
require.NoError(t, err)
defer os.RemoveAll(srcDir)
dstDir, err := ioutil.TempDir("", "dstDir")
require.NoError(t, err)
defer os.RemoveAll(dstDir)
srcFile1 := filepath.Join(srcDir, "file1")
srcFile2 := filepath.Join(srcDir, "file2")
dstFile1 := filepath.Join(dstDir, "file1")
dstFile2 := filepath.Join(dstDir, "file2")
require.NoError(t, ioutil.WriteFile(srcFile1, []byte{}, 0777))
require.NoError(t, os.Link(srcFile1, srcFile2))
assert.NoError(t, DirCopy(srcDir, dstDir, Content))
require.NoError(t, unix.Stat(srcFile1, &srcFile1FileInfo))
require.NoError(t, unix.Stat(srcFile2, &srcFile2FileInfo))
require.Equal(t, srcFile1FileInfo.Ino, srcFile2FileInfo.Ino)
require.NoError(t, unix.Stat(dstFile1, &dstFile1FileInfo))
require.NoError(t, unix.Stat(dstFile2, &dstFile2FileInfo))
assert.Equal(t, dstFile1FileInfo.Ino, dstFile2FileInfo.Ino)
}