fix: use copy when a rename spans volumes (#22995)

When a file rename fails with EXDEV
(cross device or volume error), copy the
file and delete the original instead.

closes #22890

Co-authored-by: Chris Pahl <[email protected]>

pkg/fs/fs.go

@@ -2,6 +2,10 @@ package fs
 
 import (
 	"fmt"
+	"io"
+	"os"
+
+	"github.com/influxdata/influxdb/v2/pkg/errors"
 )
 
 // A FileExistsError is returned when an operation cannot be completed due to a
@@ -25,3 +29,38 @@ type DiskStatus struct {
 	Free  uint64
 	Avail uint64
 }
+
+func copyFile(src, dst string) (err error) {
+	in, err := os.Open(src)
+	if err != nil {
+		return err
+	}
+
+	out, err := os.Create(dst)
+	if err != nil {
+		return err
+	}
+
+	defer errors.Capture(&err, out.Close)()
+
+	defer errors.Capture(&err, in.Close)()
+
+	if _, err = io.Copy(out, in); err != nil {
+		return err
+	}
+
+	return out.Sync()
+}
+
+// MoveFileWithReplacement copies the file contents at `src` to `dst`.
+// and deletes `src` on success.
+//
+// If the file at `dst` already exists, it will be truncated and its contents
+// overwritten.
+func MoveFileWithReplacement(src, dst string) error {
+	if err := copyFile(src, dst); err != nil {
+		return fmt.Errorf("copy: %w", err)
+	}
+
+	return os.Remove(src)
+}

pkg/fs/fs_test.go

@@ -10,6 +10,14 @@ import (
 )
 
 func TestRenameFileWithReplacement(t *testing.T) {
+	testFileMoveOrRename(t, "rename", fs.RenameFileWithReplacement)
+}
+
+func TestMoveFileWithReplacement(t *testing.T) {
+	testFileMoveOrRename(t, "move", fs.MoveFileWithReplacement)
+}
+
+func testFileMoveOrRename(t *testing.T, name string, testFunc func(src string, dst string) error) {
 	// sample data for loading into files
 	sampleData1 := "this is some data"
 	sampleData2 := "we got some more data"
@@ -29,8 +37,8 @@ func TestRenameFileWithReplacement(t *testing.T) {
 			t.Fatalf("got contents %q, expected %q", got, exp)
 		}
 
-		if err := fs.RenameFileWithReplacement(oldpath, newpath); err != nil {
-			t.Fatalf("ReplaceFileIfExists returned an error: %s", err)
+		if err := testFunc(oldpath, newpath); err != nil {
+			t.Fatalf("%s returned an error: %s", name, err)
 		}
 
 		if err := fs.SyncDir(filepath.Dir(oldpath)); err != nil {
@@ -60,8 +68,9 @@ func TestRenameFileWithReplacement(t *testing.T) {
 
 		root := filepath.Dir(oldpath)
 		newpath := filepath.Join(root, "foo")
-		if err := fs.RenameFileWithReplacement(oldpath, newpath); err != nil {
-			t.Fatalf("ReplaceFileIfExists returned an error: %s", err)
+
+		if err := testFunc(oldpath, newpath); err != nil {
+			t.Fatalf("%s returned an error: %s", name, err)
 		}
 
 		if err := fs.SyncDir(filepath.Dir(oldpath)); err != nil {

pkg/fs/fs_unix.go

@@ -4,6 +4,7 @@
 package fs
 
 import (
+	"errors"
 	"os"
 	"syscall"
 
@@ -34,13 +35,21 @@ func SyncDir(dirName string) error {
 }
 
 // RenameFileWithReplacement will replace any existing file at newpath with the contents
-// of oldpath.
+// of oldpath. It works also if it the rename spans over several file systems.
 //
 // If no file already exists at newpath, newpath will be created using the contents
 // of oldpath. If this function returns successfully, the contents of newpath will
 // be identical to oldpath, and oldpath will be removed.
 func RenameFileWithReplacement(oldpath, newpath string) error {
-	return os.Rename(oldpath, newpath)
+	if err := os.Rename(oldpath, newpath); !errors.Is(err, syscall.EXDEV) {
+		// note: also includes err == nil
+		return err
+	}
+
+	// move over filesystem boundaries, we have to copy.
+	// (if there was another error, it will likely fail a second time)
+	return MoveFileWithReplacement(oldpath, newpath)
+
 }
 
 // RenameFile renames oldpath to newpath, returning an error if newpath already
@@ -51,7 +60,7 @@ func RenameFile(oldpath, newpath string) error {
 		return newFileExistsError(newpath)
 	}
 
-	return os.Rename(oldpath, newpath)
+	return RenameFileWithReplacement(oldpath, newpath)
 }
 
 // CreateFile creates a new file at newpath, returning an error if newpath already