all: Add copy-on-write filesystem support (fixes #4271) (#6746)

lib/config/folderconfiguration.go

@@ -60,6 +60,7 @@ type FolderConfiguration struct {
 	MaxConcurrentWrites     int                         `xml:"maxConcurrentWrites" json:"maxConcurrentWrites" default:"2"`
 	DisableFsync            bool                        `xml:"disableFsync" json:"disableFsync"`
 	BlockPullOrder          BlockPullOrder              `xml:"blockPullOrder" json:"blockPullOrder"`
+	CopyRangeMethod         fs.CopyRangeMethod          `xml:"copyRangeMethod" json:"copyRangeMethod" default:"standard"`
 
 	cachedFilesystem    fs.Filesystem
 	cachedModTimeWindow time.Duration

lib/fs/basicfs_copy_range.go

@@ -0,0 +1,24 @@
+// Copyright (C) 2020 The Syncthing Authors.
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this file,
+// You can obtain one at https://mozilla.org/MPL/2.0/.
+
+package fs
+
+import (
+	"syscall"
+)
+
+type copyRangeImplementationBasicFile func(src, dst basicFile, srcOffset, dstOffset, size int64) error
+
+func copyRangeImplementationForBasicFile(impl copyRangeImplementationBasicFile) copyRangeImplementation {
+	return func(src, dst File, srcOffset, dstOffset, size int64) error {
+		srcFile, srcOk := src.(basicFile)
+		dstFile, dstOk := dst.(basicFile)
+		if !srcOk || !dstOk {
+			return syscall.ENOTSUP
+		}
+		return impl(srcFile, dstFile, srcOffset, dstOffset, size)
+	}
+}

lib/fs/basicfs_copy_range_copyfilerange.go

@@ -0,0 +1,45 @@
+// Copyright (C) 2019 The Syncthing Authors.
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this file,
+// You can obtain one at https://mozilla.org/MPL/2.0/.
+
+// +build linux
+
+package fs
+
+import (
+	"io"
+	"syscall"
+
+	"golang.org/x/sys/unix"
+)
+
+func init() {
+	registerCopyRangeImplementation(CopyRangeMethodCopyFileRange, copyRangeImplementationForBasicFile(copyRangeCopyFileRange))
+}
+
+func copyRangeCopyFileRange(src, dst basicFile, srcOffset, dstOffset, size int64) error {
+	for size > 0 {
+		// From MAN page:
+		//
+		// If off_in is not NULL, then off_in must point to a buffer that
+		// specifies the starting offset where bytes from fd_in will be read.
+		// 	The file offset of fd_in is not changed, but off_in is adjusted
+		// appropriately.
+		//
+		// Also, even if explicitly not stated, the same is true for dstOffset
+		n, err := unix.CopyFileRange(int(src.Fd()), &srcOffset, int(dst.Fd()), &dstOffset, int(size), 0)
+		if n == 0 && err == nil {
+			return io.ErrUnexpectedEOF
+		}
+		if err != nil && err != syscall.EAGAIN {
+			return err
+		}
+		// Handle case where err == EAGAIN and n == -1 (it's not clear if that can happen)
+		if n > 0 {
+			size -= int64(n)
+		}
+	}
+	return nil
+}

lib/fs/basicfs_copy_range_ioctl.go

@@ -0,0 +1,72 @@
+// Copyright (C) 2019 The Syncthing Authors.
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this file,
+// You can obtain one at https://mozilla.org/MPL/2.0/.
+
+// +build !windows,!solaris,!darwin
+
+package fs
+
+import (
+	"syscall"
+	"unsafe"
+)
+
+func init() {
+	registerCopyRangeImplementation(CopyRangeMethodIoctl, copyRangeImplementationForBasicFile(copyRangeIoctl))
+}
+
+const FICLONE = 0x40049409
+const FICLONERANGE = 0x4020940d
+
+/*
+http://man7.org/linux/man-pages/man2/ioctl_ficlonerange.2.html
+
+struct file_clone_range {
+   __s64 src_fd;
+   __u64 src_offset;
+   __u64 src_length;
+   __u64 dest_offset;
+};
+*/
+type fileCloneRange struct {
+	srcFd     int64
+	srcOffset uint64
+	srcLength uint64
+	dstOffset uint64
+}
+
+func copyRangeIoctl(src, dst basicFile, srcOffset, dstOffset, size int64) error {
+	fi, err := src.Stat()
+	if err != nil {
+		return err
+	}
+
+	// https://www.man7.org/linux/man-pages/man2/ioctl_ficlonerange.2.html
+	// If src_length is zero, the ioctl reflinks to the end of the source file.
+	if srcOffset+size == fi.Size() {
+		size = 0
+	}
+
+	if srcOffset == 0 && dstOffset == 0 && size == 0 {
+		// Optimization for whole file copies.
+		_, _, errNo := syscall.Syscall(syscall.SYS_IOCTL, dst.Fd(), FICLONE, src.Fd())
+		if errNo != 0 {
+			return errNo
+		}
+		return nil
+	}
+
+	params := fileCloneRange{
+		srcFd:     int64(src.Fd()),
+		srcOffset: uint64(srcOffset),
+		srcLength: uint64(size),
+		dstOffset: uint64(dstOffset),
+	}
+	_, _, errNo := syscall.Syscall(syscall.SYS_IOCTL, dst.Fd(), FICLONERANGE, uintptr(unsafe.Pointer(&params)))
+	if errNo != 0 {
+		return errNo
+	}
+	return nil
+}

lib/fs/basicfs_copy_range_sendfile.go

@@ -0,0 +1,69 @@
+// Copyright (C) 2019 The Syncthing Authors.
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this file,
+// You can obtain one at https://mozilla.org/MPL/2.0/.
+
+// +build !windows,!darwin
+
+package fs
+
+import (
+	"io"
+	"syscall"
+)
+
+func init() {
+	registerCopyRangeImplementation(CopyRangeMethodSendFile, copyRangeImplementationForBasicFile(copyRangeSendFile))
+}
+
+func copyRangeSendFile(src, dst basicFile, srcOffset, dstOffset, size int64) error {
+	// Check that the destination file has sufficient space
+	if fi, err := dst.Stat(); err != nil {
+		return err
+	} else if fi.Size() < dstOffset+size {
+		if err := dst.Truncate(dstOffset + size); err != nil {
+			return err
+		}
+	}
+
+	// Record old dst offset.
+	oldDstOffset, err := dst.Seek(0, io.SeekCurrent)
+	if err != nil {
+		return err
+	}
+	defer func() { _, _ = dst.Seek(oldDstOffset, io.SeekStart) }()
+
+	// Seek to the offset we expect to write
+	if oldDstOffset != dstOffset {
+		if n, err := dst.Seek(dstOffset, io.SeekStart); err != nil {
+			return err
+		} else if n != dstOffset {
+			return io.ErrUnexpectedEOF
+		}
+	}
+
+	for size > 0 {
+		// From the MAN page:
+		//
+		// If offset is not NULL, then it points to a variable holding the file offset from which sendfile() will start
+		// reading data from in_fd. When sendfile() returns, this variable will be set to the offset of the byte
+		// following the last byte that was read. If offset is not NULL, then sendfile() does not modify the current
+		// file offset of in_fd; otherwise the current file offset is adjusted to reflect the number of bytes read from
+		// in_fd.
+		n, err := syscall.Sendfile(int(dst.Fd()), int(src.Fd()), &srcOffset, int(size))
+		if n == 0 && err == nil {
+			err = io.ErrUnexpectedEOF
+		}
+		if err != nil && err != syscall.EAGAIN {
+			return err
+		}
+		// Handle case where err == EAGAIN and n == -1 (it's not clear if that can happen)
+		if n > 0 {
+			size -= int64(n)
+		}
+	}
+
+	_, err = dst.Seek(oldDstOffset, io.SeekStart)
+	return err
+}

lib/fs/filesystem_copy_range.go

@@ -0,0 +1,45 @@
+// Copyright (C) 2019 The Syncthing Authors.
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this file,
+// You can obtain one at https://mozilla.org/MPL/2.0/.
+
+package fs
+
+import (
+	"syscall"
+
+	"github.com/syncthing/syncthing/lib/sync"
+)
+
+var (
+	copyRangeMethods = make(map[CopyRangeMethod]copyRangeImplementation)
+	mut              = sync.NewMutex()
+)
+
+type copyRangeImplementation func(src, dst File, srcOffset, dstOffset, size int64) error
+
+func registerCopyRangeImplementation(copyMethod CopyRangeMethod, impl copyRangeImplementation) {
+	mut.Lock()
+	defer mut.Unlock()
+
+	l.Debugln("Registering " + copyMethod.String() + " copyRange method")
+
+	copyRangeMethods[copyMethod] = impl
+}
+
+// CopyRange tries to use the specified method to copy data between two files.
+// Takes size bytes at offset srcOffset from the source file, and copies the data to destination file at offset
+// dstOffset. If required, adjusts the size of the destination file to fit that much data.
+//
+// On Linux/BSD you can ask it to use ioctl and copy_file_range system calls, which if the underlying filesystem supports
+// it tries referencing existing data in the source file, instead of making a copy and taking up additional space.
+//
+// CopyRange does its best to have no effect on src and dst file offsets (copy operation should not affect it).
+func CopyRange(copyMethod CopyRangeMethod, src, dst File, srcOffset, dstOffset, size int64) error {
+	if impl, ok := copyRangeMethods[copyMethod]; ok {
+		return impl(src, dst, srcOffset, dstOffset, size)
+	}
+
+	return syscall.ENOTSUP
+}

lib/fs/filesystem_copy_range_allwithfallback.go

@@ -0,0 +1,21 @@
+// Copyright (C) 2019 The Syncthing Authors.
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this file,
+// You can obtain one at https://mozilla.org/MPL/2.0/.
+
+package fs
+
+func init() {
+	registerCopyRangeImplementation(CopyRangeMethodAllWithFallback, copyRangeAllWithFallback)
+}
+
+func copyRangeAllWithFallback(src, dst File, srcOffset, dstOffset, size int64) error {
+	var err error
+	for _, method := range []CopyRangeMethod{CopyRangeMethodIoctl, CopyRangeMethodCopyFileRange, CopyRangeMethodSendFile, CopyRangeMethodStandard} {
+		if err = CopyRange(method, src, dst, srcOffset, dstOffset, size); err == nil {
+			return nil
+		}
+	}
+	return err
+}

lib/fs/filesystem_copy_range_method.go

@@ -0,0 +1,60 @@
+// Copyright (C) 2020 The Syncthing Authors.
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this file,
+// You can obtain one at https://mozilla.org/MPL/2.0/.
+
+package fs
+
+type CopyRangeMethod int
+
+const (
+	CopyRangeMethodStandard CopyRangeMethod = iota
+	CopyRangeMethodIoctl
+	CopyRangeMethodCopyFileRange
+	CopyRangeMethodSendFile
+	CopyRangeMethodAllWithFallback
+)
+
+func (o CopyRangeMethod) String() string {
+	switch o {
+	case CopyRangeMethodStandard:
+		return "standard"
+	case CopyRangeMethodIoctl:
+		return "ioctl"
+	case CopyRangeMethodCopyFileRange:
+		return "copy_file_range"
+	case CopyRangeMethodSendFile:
+		return "sendfile"
+	case CopyRangeMethodAllWithFallback:
+		return "all"
+	default:
+		return "unknown"
+	}
+}
+
+func (o CopyRangeMethod) MarshalText() ([]byte, error) {
+	return []byte(o.String()), nil
+}
+
+func (o *CopyRangeMethod) UnmarshalText(bs []byte) error {
+	switch string(bs) {
+	case "standard":
+		*o = CopyRangeMethodStandard
+	case "ioctl":
+		*o = CopyRangeMethodIoctl
+	case "copy_file_range":
+		*o = CopyRangeMethodCopyFileRange
+	case "sendfile":
+		*o = CopyRangeMethodSendFile
+	case "all":
+		*o = CopyRangeMethodAllWithFallback
+	default:
+		*o = CopyRangeMethodStandard
+	}
+	return nil
+}
+
+func (o *CopyRangeMethod) ParseDefault(str string) error {
+	return o.UnmarshalText([]byte(str))
+}

lib/fs/filesystem_copy_range_standard.go

@@ -0,0 +1,45 @@
+// Copyright (C) 2019 The Syncthing Authors.
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this file,
+// You can obtain one at https://mozilla.org/MPL/2.0/.
+
+package fs
+
+import (
+	"io"
+)
+
+func init() {
+	registerCopyRangeImplementation(CopyRangeMethodStandard, copyRangeStandard)
+}
+
+func copyRangeStandard(src, dst File, srcOffset, dstOffset, size int64) error {
+	const bufSize = 4 << 20
+
+	buf := make([]byte, bufSize)
+
+	// TODO: In go 1.15, we should use file.ReadFrom that uses copy_file_range underneath.
+
+	// ReadAt and WriteAt does not modify the position of the file.
+	for size > 0 {
+		if size < bufSize {
+			buf = buf[:size]
+		}
+		n, err := src.ReadAt(buf, srcOffset)
+		if err != nil {
+			if err == io.EOF {
+				return io.ErrUnexpectedEOF
+			}
+			return err
+		}
+		if _, err = dst.WriteAt(buf[:n], dstOffset); err != nil {
+			return err
+		}
+		srcOffset += int64(n)
+		dstOffset += int64(n)
+		size -= int64(n)
+	}
+
+	return nil
+}

lib/fs/filesystem_copy_range_test.go

@@ -0,0 +1,322 @@
+// Copyright (C) 2019 The Syncthing Authors.
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this file,
+// You can obtain one at https://mozilla.org/MPL/2.0/.
+
+package fs
+
+import (
+	"bytes"
+	"io"
+	"io/ioutil"
+	"math/rand"
+	"os"
+	"syscall"
+	"testing"
+)
+
+var (
+	generationSize  int64 = 4 << 20
+	defaultCopySize int64 = 1 << 20
+
+	testCases = []struct {
+		name string
+		// Starting size of files
+		srcSize int64
+		dstSize int64
+		// Offset from which to read
+		srcOffset int64
+		dstOffset int64
+		// Cursor position before the copy
+		srcStartingPos int64
+		dstStartingPos int64
+		// Expected destination size
+		expectedDstSizeAfterCopy int64
+		// Custom copy size
+		copySize int64
+		// Expected failure
+		expectedErrors map[CopyRangeMethod]error
+	}{
+		{
+			name:                     "append to end",
+			srcSize:                  generationSize,
+			dstSize:                  generationSize,
+			srcOffset:                0,
+			dstOffset:                generationSize,
+			srcStartingPos:           generationSize,
+			dstStartingPos:           generationSize,
+			expectedDstSizeAfterCopy: generationSize + defaultCopySize,
+			copySize:                 defaultCopySize,
+			expectedErrors:           nil,
+		},
+		{
+			name:                     "append to end, offsets at start",
+			srcSize:                  generationSize,
+			dstSize:                  generationSize,
+			srcOffset:                0,
+			dstOffset:                generationSize,
+			srcStartingPos:           0, // We seek back to start, and expect src not to move after copy
+			dstStartingPos:           0, // Seek back, but expect dst pos to not change
+			expectedDstSizeAfterCopy: generationSize + defaultCopySize,
+			copySize:                 defaultCopySize,
+			expectedErrors:           nil,
+		},
+		{
+			name:                     "overwrite part of destination region",
+			srcSize:                  generationSize,
+			dstSize:                  generationSize,
+			srcOffset:                defaultCopySize,
+			dstOffset:                generationSize,
+			srcStartingPos:           generationSize,
+			dstStartingPos:           generationSize,
+			expectedDstSizeAfterCopy: generationSize + defaultCopySize,
+			copySize:                 defaultCopySize,
+			expectedErrors:           nil,
+		},
+		{
+			name:                     "overwrite all of destination",
+			srcSize:                  generationSize,
+			dstSize:                  generationSize,
+			srcOffset:                0,
+			dstOffset:                0,
+			srcStartingPos:           generationSize,
+			dstStartingPos:           generationSize,
+			expectedDstSizeAfterCopy: generationSize,
+			copySize:                 defaultCopySize,
+			expectedErrors:           nil,
+		},
+		{
+			name:                     "overwrite part of destination",
+			srcSize:                  generationSize,
+			dstSize:                  generationSize,
+			srcOffset:                defaultCopySize,
+			dstOffset:                0,
+			srcStartingPos:           generationSize,
+			dstStartingPos:           generationSize,
+			expectedDstSizeAfterCopy: generationSize,
+			copySize:                 defaultCopySize,
+			expectedErrors:           nil,
+		},
+		// Write way past the end of the file
+		{
+			name:                     "destination gets expanded as it is being written to",
+			srcSize:                  generationSize,
+			dstSize:                  generationSize,
+			srcOffset:                0,
+			dstOffset:                generationSize * 2,
+			srcStartingPos:           generationSize,
+			dstStartingPos:           generationSize,
+			expectedDstSizeAfterCopy: generationSize*2 + defaultCopySize,
+			copySize:                 defaultCopySize,
+			expectedErrors:           nil,
+		},
+		// Source file does not have enough bytes to copy in that range, should result in an unexpected eof.
+		{
+			name:                     "source file too small",
+			srcSize:                  generationSize,
+			dstSize:                  generationSize,
+			srcOffset:                0,
+			dstOffset:                0,
+			srcStartingPos:           0,
+			dstStartingPos:           0,
+			expectedDstSizeAfterCopy: -11, // Does not matter, should fail.
+			copySize:                 defaultCopySize * 10,
+			// ioctl returns syscall.EINVAL, rest are wrapped
+			expectedErrors: map[CopyRangeMethod]error{
+				CopyRangeMethodIoctl:           syscall.EINVAL,
+				CopyRangeMethodStandard:        io.ErrUnexpectedEOF,
+				CopyRangeMethodCopyFileRange:   io.ErrUnexpectedEOF,
+				CopyRangeMethodSendFile:        io.ErrUnexpectedEOF,
+				CopyRangeMethodAllWithFallback: io.ErrUnexpectedEOF,
+			},
+		},
+		// Non block sized file
+		{
+			name:                     "not block aligned write",
+			srcSize:                  generationSize + 2,
+			dstSize:                  0,
+			srcOffset:                1,
+			dstOffset:                0,
+			srcStartingPos:           0,
+			dstStartingPos:           0,
+			expectedDstSizeAfterCopy: generationSize + 1,
+			copySize:                 generationSize + 1,
+			// Only fails for ioctl
+			expectedErrors: map[CopyRangeMethod]error{
+				CopyRangeMethodIoctl: syscall.EINVAL,
+			},
+		},
+		// Last block that starts on a nice boundary
+		{
+			name:                     "last block",
+			srcSize:                  generationSize + 2,
+			dstSize:                  0,
+			srcOffset:                generationSize,
+			dstOffset:                0,
+			srcStartingPos:           0,
+			dstStartingPos:           0,
+			expectedDstSizeAfterCopy: 2,
+			copySize:                 2,
+			// Succeeds on all, as long as the offset is file-system block aligned.
+			expectedErrors: nil,
+		},
+		// Copy whole file
+		{
+			name:                     "whole file copy block aligned",
+			srcSize:                  generationSize,
+			dstSize:                  0,
+			srcOffset:                0,
+			dstOffset:                0,
+			srcStartingPos:           0,
+			dstStartingPos:           0,
+			expectedDstSizeAfterCopy: generationSize,
+			copySize:                 generationSize,
+			expectedErrors:           nil,
+		},
+		{
+			name:                     "whole file copy not block aligned",
+			srcSize:                  generationSize + 1,
+			dstSize:                  0,
+			srcOffset:                0,
+			dstOffset:                0,
+			srcStartingPos:           0,
+			dstStartingPos:           0,
+			expectedDstSizeAfterCopy: generationSize + 1,
+			copySize:                 generationSize + 1,
+			expectedErrors:           nil,
+		},
+	}
+)
+
+func TestCopyRange(ttt *testing.T) {
+	randSrc := rand.New(rand.NewSource(rand.Int63()))
+	for copyMethod, impl := range copyRangeMethods {
+		ttt.Run(copyMethod.String(), func(tt *testing.T) {
+			for _, testCase := range testCases {
+				tt.Run(testCase.name, func(t *testing.T) {
+					srcBuf := make([]byte, testCase.srcSize)
+					dstBuf := make([]byte, testCase.dstSize)
+					td, err := ioutil.TempDir(os.Getenv("STFSTESTPATH"), "")
+					if err != nil {
+						t.Fatal(err)
+					}
+					defer func() { _ = os.RemoveAll(td) }()
+					fs := NewFilesystem(FilesystemTypeBasic, td)
+
+					if _, err := io.ReadFull(randSrc, srcBuf); err != nil {
+						t.Fatal(err)
+					}
+
+					if _, err := io.ReadFull(randSrc, dstBuf); err != nil {
+						t.Fatal(err)
+					}
+
+					src, err := fs.Create("src")
+					if err != nil {
+						t.Fatal(err)
+					}
+					defer func() { _ = src.Close() }()
+
+					dst, err := fs.Create("dst")
+					if err != nil {
+						t.Fatal(err)
+					}
+					defer func() { _ = dst.Close() }()
+
+					// Write some data
+
+					if _, err := src.Write(srcBuf); err != nil {
+						t.Fatal(err)
+					}
+
+					if _, err := dst.Write(dstBuf); err != nil {
+						t.Fatal(err)
+					}
+
+					// Set the offsets
+
+					if n, err := src.Seek(testCase.srcStartingPos, io.SeekStart); err != nil || n != testCase.srcStartingPos {
+						t.Fatal(err)
+					}
+
+					if n, err := dst.Seek(testCase.dstStartingPos, io.SeekStart); err != nil || n != testCase.dstStartingPos {
+						t.Fatal(err)
+					}
+
+					if err := impl(src.(basicFile), dst.(basicFile), testCase.srcOffset, testCase.dstOffset, testCase.copySize); err != nil {
+						if err == syscall.ENOTSUP {
+							// Test runner can adjust directory in which to run the tests, that allow broader tests.
+							t.Skip("Not supported on the current filesystem, set STFSTESTPATH env var.")
+						}
+						if testCase.expectedErrors[copyMethod] == err {
+							return
+						}
+						t.Fatal(err)
+					} else if testCase.expectedErrors[copyMethod] != nil {
+						t.Fatal("did not get expected error")
+					}
+
+					// Check offsets where we expect them
+
+					if srcCurPos, err := src.Seek(0, io.SeekCurrent); err != nil {
+						t.Fatal(err)
+					} else if srcCurPos != testCase.srcStartingPos {
+						t.Errorf("src pos expected %d got %d", testCase.srcStartingPos, srcCurPos)
+					}
+
+					if dstCurPos, err := dst.Seek(0, io.SeekCurrent); err != nil {
+						t.Fatal(err)
+					} else if dstCurPos != testCase.dstStartingPos {
+						t.Errorf("dst pos expected %d got %d", testCase.dstStartingPos, dstCurPos)
+					}
+
+					// Check dst size
+
+					if fi, err := dst.Stat(); err != nil {
+						t.Fatal(err)
+					} else if fi.Size() != testCase.expectedDstSizeAfterCopy {
+						t.Errorf("expected %d size, got %d", testCase.expectedDstSizeAfterCopy, fi.Size())
+					}
+
+					// Check the data is as expected
+
+					if _, err := dst.Seek(0, io.SeekStart); err != nil {
+						t.Fatal(err)
+					}
+
+					resultBuf := make([]byte, testCase.expectedDstSizeAfterCopy)
+					if _, err := io.ReadFull(dst, resultBuf); err != nil {
+						t.Fatal(err)
+					}
+
+					if !bytes.Equal(srcBuf[testCase.srcOffset:testCase.srcOffset+testCase.copySize], resultBuf[testCase.dstOffset:testCase.dstOffset+testCase.copySize]) {
+						t.Errorf("Not equal")
+					}
+
+					// Check not copied content does not get corrupted
+
+					if testCase.dstOffset > testCase.dstSize {
+						if !bytes.Equal(dstBuf[:testCase.dstSize], resultBuf[:testCase.dstSize]) {
+							t.Error("region before copy region not equals")
+						}
+						if !bytes.Equal(resultBuf[testCase.dstSize:testCase.dstOffset], make([]byte, testCase.dstOffset-testCase.dstSize)) {
+							t.Error("found non zeroes in expected zero region")
+						}
+					} else {
+						if !bytes.Equal(dstBuf[:testCase.dstOffset], resultBuf[:testCase.dstOffset]) {
+							t.Error("region before copy region not equals")
+						}
+						afterCopyStart := testCase.dstOffset + testCase.copySize
+
+						if afterCopyStart < testCase.dstSize {
+							if !bytes.Equal(dstBuf[afterCopyStart:], resultBuf[afterCopyStart:len(dstBuf)]) {
+								t.Error("region after copy region not equals")
+							}
+						}
+					}
+				})
+			}
+		})
+	}
+}

lib/model/folder_sendrecv.go

@@ -986,13 +986,13 @@ func (f *sendReceiveFolder) renameFile(cur, source, target protocol.FileInfo, sn
 	if f.versioner != nil {
 		err = f.CheckAvailableSpace(source.Size)
 		if err == nil {
-			err = osutil.Copy(f.fs, f.fs, source.Name, tempName)
+			err = osutil.Copy(f.CopyRangeMethod, f.fs, f.fs, source.Name, tempName)
 			if err == nil {
 				err = f.inWritableDir(f.versioner.Archive, source.Name)
 			}
 		}
 	} else {
-		err = osutil.RenameOrCopy(f.fs, f.fs, source.Name, tempName)
+		err = osutil.RenameOrCopy(f.CopyRangeMethod, f.fs, f.fs, source.Name, tempName)
 	}
 	if err != nil {
 		return err
@@ -1296,7 +1296,7 @@ func (f *sendReceiveFolder) copierRoutine(in <-chan copyBlocksState, pullChan ch
 					return true
 				}
 
-				_, err = f.limitedWriteAt(dstFd, buf, block.Offset)
+				err = f.limitedWriteAt(dstFd, buf, block.Offset)
 				if err != nil {
 					state.fail(errors.Wrap(err, "dst write"))
 				}
@@ -1314,13 +1314,14 @@ func (f *sendReceiveFolder) copierRoutine(in <-chan copyBlocksState, pullChan ch
 
 			if !found {
 				found = f.model.finder.Iterate(folders, block.Hash, func(folder, path string, index int32) bool {
-					fs := folderFilesystems[folder]
-					fd, err := fs.Open(path)
+					ffs := folderFilesystems[folder]
+					fd, err := ffs.Open(path)
 					if err != nil {
 						return false
 					}
 
-					_, err = fd.ReadAt(buf, int64(state.file.BlockSize())*int64(index))
+					srcOffset := int64(state.file.BlockSize()) * int64(index)
+					_, err = fd.ReadAt(buf, srcOffset)
 					fd.Close()
 					if err != nil {
 						return false
@@ -1331,7 +1332,15 @@ func (f *sendReceiveFolder) copierRoutine(in <-chan copyBlocksState, pullChan ch
 						return false
 					}
 
-					_, err = f.limitedWriteAt(dstFd, buf, block.Offset)
+					if f.CopyRangeMethod != fs.CopyRangeMethodStandard {
+						err = f.withLimiter(func() error {
+							dstFd.mut.Lock()
+							defer dstFd.mut.Unlock()
+							return fs.CopyRange(f.CopyRangeMethod, fd, dstFd.fd, srcOffset, block.Offset, int64(block.Size))
+						})
+					} else {
+						err = f.limitedWriteAt(dstFd, buf, block.Offset)
+					}
 					if err != nil {
 						state.fail(errors.Wrap(err, "dst write"))
 					}
@@ -1480,7 +1489,7 @@ func (f *sendReceiveFolder) pullBlock(state pullBlockState, out chan<- *sharedPu
 		}
 
 		// Save the block data we got from the cluster
-		_, err = f.limitedWriteAt(fd, buf, state.block.Offset)
+		err = f.limitedWriteAt(fd, buf, state.block.Offset)
 		if err != nil {
 			state.fail(errors.Wrap(err, "save"))
 		} else {
@@ -1535,7 +1544,7 @@ func (f *sendReceiveFolder) performFinish(file, curFile protocol.FileInfo, hasCu
 
 	// Replace the original content with the new one. If it didn't work,
 	// leave the temp file in place for reuse.
-	if err := osutil.RenameOrCopy(f.fs, f.fs, tempName, file.Name); err != nil {
+	if err := osutil.RenameOrCopy(f.CopyRangeMethod, f.fs, f.fs, tempName, file.Name); err != nil {
 		return err
 	}
 
@@ -2006,12 +2015,19 @@ func (f *sendReceiveFolder) inWritableDir(fn func(string) error, path string) er
 	return inWritableDir(fn, f.fs, path, f.IgnorePerms)
 }
 
-func (f *sendReceiveFolder) limitedWriteAt(fd io.WriterAt, data []byte, offset int64) (int, error) {
+func (f *sendReceiveFolder) limitedWriteAt(fd io.WriterAt, data []byte, offset int64) error {
+	return f.withLimiter(func() error {
+		_, err := fd.WriteAt(data, offset)
+		return err
+	})
+}
+
+func (f *sendReceiveFolder) withLimiter(fn func() error) error {
 	if err := f.writeLimiter.takeWithContext(f.ctx, 1); err != nil {
-		return 0, err
+		return err
 	}
 	defer f.writeLimiter.give(1)
-	return fd.WriteAt(data, offset)
+	return fn()
 }
 
 // A []FileError is sent as part of an event and will be JSON serialized.

lib/model/folder_sendrecv_test.go

@@ -980,7 +980,7 @@ func TestDeleteBehindSymlink(t *testing.T) {
 	must(t, ffs.MkdirAll(link, 0755))
 	fi := createFile(t, file, ffs)
 	f.updateLocalsFromScanning([]protocol.FileInfo{fi})
-	must(t, osutil.RenameOrCopy(ffs, destFs, file, "file"))
+	must(t, osutil.RenameOrCopy(fs.CopyRangeMethodStandard, ffs, destFs, file, "file"))
 	must(t, ffs.RemoveAll(link))
 
 	if err := osutil.DebugSymlinkForTestsOnly(destFs.URI(), filepath.Join(ffs.URI(), link)); err != nil {

lib/model/model.go

@@ -341,7 +341,7 @@ func (m *model) addAndStartFolderLockedWithIgnores(cfg config.FolderConfiguratio
 	var ver versioner.Versioner
 	if cfg.Versioning.Type != "" {
 		var err error
-		ver, err = versioner.New(ffs, cfg.Versioning)
+		ver, err = versioner.New(cfg)
 		if err != nil {
 			panic(fmt.Errorf("creating versioner: %w", err))
 		}

lib/model/model_test.go

@@ -3636,10 +3636,10 @@ func TestRenameSameFile(t *testing.T) {
 	}
 
 	must(t, ffs.Rename("file", "file1"))
-	must(t, osutil.Copy(ffs, ffs, "file1", "file0"))
-	must(t, osutil.Copy(ffs, ffs, "file1", "file2"))
-	must(t, osutil.Copy(ffs, ffs, "file1", "file3"))
-	must(t, osutil.Copy(ffs, ffs, "file1", "file4"))
+	must(t, osutil.Copy(fs.CopyRangeMethodStandard, ffs, ffs, "file1", "file0"))
+	must(t, osutil.Copy(fs.CopyRangeMethodStandard, ffs, ffs, "file1", "file2"))
+	must(t, osutil.Copy(fs.CopyRangeMethodStandard, ffs, ffs, "file1", "file3"))
+	must(t, osutil.Copy(fs.CopyRangeMethodStandard, ffs, ffs, "file1", "file4"))
 
 	m.ScanFolders()
 

lib/model/sharedpullerstate.go

@@ -7,7 +7,6 @@
 package model
 
 import (
-	"io"
 	"time"
 
 	"github.com/pkg/errors"
@@ -118,7 +117,7 @@ func (w *lockedWriterAt) SyncClose(fsync bool) error {
 
 // tempFile returns the fd for the temporary file, reusing an open fd
 // or creating the file as necessary.
-func (s *sharedPullerState) tempFile() (io.WriterAt, error) {
+func (s *sharedPullerState) tempFile() (*lockedWriterAt, error) {
 	s.mut.Lock()
 	defer s.mut.Unlock()
 

lib/osutil/osutil.go

@@ -8,7 +8,6 @@
 package osutil
 
 import (
-	"io"
 	"path/filepath"
 	"runtime"
 	"strings"
@@ -24,7 +23,7 @@ var renameLock = sync.NewMutex()
 // RenameOrCopy renames a file, leaving source file intact in case of failure.
 // Tries hard to succeed on various systems by temporarily tweaking directory
 // permissions and removing the destination file when necessary.
-func RenameOrCopy(src, dst fs.Filesystem, from, to string) error {
+func RenameOrCopy(method fs.CopyRangeMethod, src, dst fs.Filesystem, from, to string) error {
 	renameLock.Lock()
 	defer renameLock.Unlock()
 
@@ -59,7 +58,7 @@ func RenameOrCopy(src, dst fs.Filesystem, from, to string) error {
 			}
 		}
 
-		err := copyFileContents(src, dst, from, to)
+		err := copyFileContents(method, src, dst, from, to)
 		if err != nil {
 			_ = dst.Remove(to)
 			return err
@@ -74,9 +73,9 @@ func RenameOrCopy(src, dst fs.Filesystem, from, to string) error {
 // Copy copies the file content from source to destination.
 // Tries hard to succeed on various systems by temporarily tweaking directory
 // permissions and removing the destination file when necessary.
-func Copy(src, dst fs.Filesystem, from, to string) (err error) {
+func Copy(method fs.CopyRangeMethod, src, dst fs.Filesystem, from, to string) (err error) {
 	return withPreparedTarget(dst, from, to, func() error {
-		return copyFileContents(src, dst, from, to)
+		return copyFileContents(method, src, dst, from, to)
 	})
 }
 
@@ -107,7 +106,7 @@ func withPreparedTarget(filesystem fs.Filesystem, from, to string, f func() erro
 // by dst. The file will be created if it does not already exist. If the
 // destination file exists, all its contents will be replaced by the contents
 // of the source file.
-func copyFileContents(srcFs, dstFs fs.Filesystem, src, dst string) (err error) {
+func copyFileContents(method fs.CopyRangeMethod, srcFs, dstFs fs.Filesystem, src, dst string) (err error) {
 	in, err := srcFs.Open(src)
 	if err != nil {
 		return
@@ -123,7 +122,11 @@ func copyFileContents(srcFs, dstFs fs.Filesystem, src, dst string) (err error) {
 			err = cerr
 		}
 	}()
-	_, err = io.Copy(out, in)
+	inFi, err := in.Stat()
+	if err != nil {
+		return
+	}
+	err = fs.CopyRange(method, in, out, 0, 0, inFi.Size())
 	return
 }
 

lib/osutil/osutil_test.go

@@ -139,7 +139,7 @@ func TestRenameOrCopy(t *testing.T) {
 			content = string(buf)
 		}
 
-		err := osutil.RenameOrCopy(test.src, test.dst, test.file, "new")
+		err := osutil.RenameOrCopy(fs.CopyRangeMethodStandard, test.src, test.dst, test.file, "new")
 		if err != nil {
 			t.Fatal(err)
 		}

lib/versioner/external.go

@@ -14,6 +14,7 @@ import (
 	"strings"
 	"time"
 
+	"github.com/syncthing/syncthing/lib/config"
 	"github.com/syncthing/syncthing/lib/fs"
 
 	"github.com/kballard/go-shellquote"
@@ -29,8 +30,8 @@ type external struct {
 	filesystem fs.Filesystem
 }
 
-func newExternal(filesystem fs.Filesystem, params map[string]string) Versioner {
-	command := params["command"]
+func newExternal(cfg config.FolderConfiguration) Versioner {
+	command := cfg.Versioning.Params["command"]
 
 	if runtime.GOOS == "windows" {
 		command = strings.Replace(command, `\`, `\\`, -1)
@@ -38,7 +39,7 @@ func newExternal(filesystem fs.Filesystem, params map[string]string) Versioner {
 
 	s := external{
 		command:    command,
-		filesystem: filesystem,
+		filesystem: cfg.Filesystem(),
 	}
 
 	l.Debugf("instantiated %#v", s)

lib/versioner/simple.go

@@ -10,6 +10,7 @@ import (
 	"strconv"
 	"time"
 
+	"github.com/syncthing/syncthing/lib/config"
 	"github.com/syncthing/syncthing/lib/fs"
 )
 
@@ -19,21 +20,23 @@ func init() {
 }
 
 type simple struct {
-	keep       int
-	folderFs   fs.Filesystem
-	versionsFs fs.Filesystem
+	keep            int
+	folderFs        fs.Filesystem
+	versionsFs      fs.Filesystem
+	copyRangeMethod fs.CopyRangeMethod
 }
 
-func newSimple(folderFs fs.Filesystem, params map[string]string) Versioner {
-	keep, err := strconv.Atoi(params["keep"])
+func newSimple(cfg config.FolderConfiguration) Versioner {
+	var keep, err = strconv.Atoi(cfg.Versioning.Params["keep"])
 	if err != nil {
 		keep = 5 // A reasonable default
 	}
 
 	s := simple{
-		keep:       keep,
-		folderFs:   folderFs,
-		versionsFs: fsFromParams(folderFs, params),
+		keep:            keep,
+		folderFs:        cfg.Filesystem(),
+		versionsFs:      versionerFsFromFolderCfg(cfg),
+		copyRangeMethod: cfg.CopyRangeMethod,
 	}
 
 	l.Debugf("instantiated %#v", s)
@@ -43,7 +46,7 @@ func newSimple(folderFs fs.Filesystem, params map[string]string) Versioner {
 // Archive moves the named file away to a version archive. If this function
 // returns nil, the named file does not exist any more (has been archived).
 func (v simple) Archive(filePath string) error {
-	err := archiveFile(v.folderFs, v.versionsFs, filePath, TagFilename)
+	err := archiveFile(v.copyRangeMethod, v.folderFs, v.versionsFs, filePath, TagFilename)
 	if err != nil {
 		return err
 	}
@@ -68,5 +71,5 @@ func (v simple) GetVersions() (map[string][]FileVersion, error) {
 }
 
 func (v simple) Restore(filepath string, versionTime time.Time) error {
-	return restoreFile(v.versionsFs, v.folderFs, filepath, versionTime, TagFilename)
+	return restoreFile(v.copyRangeMethod, v.versionsFs, v.folderFs, filepath, versionTime, TagFilename)
 }

lib/versioner/simple_test.go

@@ -7,6 +7,7 @@
 package versioner
 
 import (
+	"github.com/syncthing/syncthing/lib/config"
 	"io/ioutil"
 	"math"
 	"path/filepath"
@@ -59,9 +60,18 @@ func TestSimpleVersioningVersionCount(t *testing.T) {
 		t.Error(err)
 	}
 
-	fs := fs.NewFilesystem(fs.FilesystemTypeBasic, dir)
+	cfg := config.FolderConfiguration{
+		FilesystemType: fs.FilesystemTypeBasic,
+		Path:           dir,
+		Versioning: config.VersioningConfiguration{
+			Params: map[string]string{
+				"keep": "2",
+			},
+		},
+	}
+	fs := cfg.Filesystem()
 
-	v := newSimple(fs, map[string]string{"keep": "2"})
+	v := newSimple(cfg)
 
 	path := "test"
 

lib/versioner/staggered.go

@@ -15,6 +15,7 @@ import (
 
 	"github.com/thejerf/suture"
 
+	"github.com/syncthing/syncthing/lib/config"
 	"github.com/syncthing/syncthing/lib/fs"
 	"github.com/syncthing/syncthing/lib/sync"
 	"github.com/syncthing/syncthing/lib/util"
@@ -32,16 +33,18 @@ type interval struct {
 
 type staggered struct {
 	suture.Service
-	cleanInterval int64
-	folderFs      fs.Filesystem
-	versionsFs    fs.Filesystem
-	interval      [4]interval
-	mutex         sync.Mutex
+	cleanInterval   int64
+	folderFs        fs.Filesystem
+	versionsFs      fs.Filesystem
+	interval        [4]interval
+	copyRangeMethod fs.CopyRangeMethod
+	mutex           sync.Mutex
 
 	testCleanDone chan struct{}
 }
 
-func newStaggered(folderFs fs.Filesystem, params map[string]string) Versioner {
+func newStaggered(cfg config.FolderConfiguration) Versioner {
+	params := cfg.Versioning.Params
 	maxAge, err := strconv.ParseInt(params["maxAge"], 10, 0)
 	if err != nil {
 		maxAge = 31536000 // Default: ~1 year
@@ -53,11 +56,11 @@ func newStaggered(folderFs fs.Filesystem, params map[string]string) Versioner {
 
 	// Backwards compatibility
 	params["fsPath"] = params["versionsPath"]
-	versionsFs := fsFromParams(folderFs, params)
+	versionsFs := versionerFsFromFolderCfg(cfg)
 
 	s := &staggered{
 		cleanInterval: cleanInterval,
-		folderFs:      folderFs,
+		folderFs:      cfg.Filesystem(),
 		versionsFs:    versionsFs,
 		interval: [4]interval{
 			{30, 60 * 60},                     // first hour -> 30 sec between versions
@@ -65,7 +68,8 @@ func newStaggered(folderFs fs.Filesystem, params map[string]string) Versioner {
 			{24 * 60 * 60, 30 * 24 * 60 * 60}, // next 30 days -> 1 day between versions
 			{7 * 24 * 60 * 60, maxAge},        // next year -> 1 week between versions
 		},
-		mutex: sync.NewMutex(),
+		copyRangeMethod: cfg.CopyRangeMethod,
+		mutex:           sync.NewMutex(),
 	}
 	s.Service = util.AsService(s.serve, s.String())
 
@@ -216,7 +220,7 @@ func (v *staggered) Archive(filePath string) error {
 	v.mutex.Lock()
 	defer v.mutex.Unlock()
 
-	if err := archiveFile(v.folderFs, v.versionsFs, filePath, TagFilename); err != nil {
+	if err := archiveFile(v.copyRangeMethod, v.folderFs, v.versionsFs, filePath, TagFilename); err != nil {
 		return err
 	}
 
@@ -230,7 +234,7 @@ func (v *staggered) GetVersions() (map[string][]FileVersion, error) {
 }
 
 func (v *staggered) Restore(filepath string, versionTime time.Time) error {
-	return restoreFile(v.versionsFs, v.folderFs, filepath, versionTime, TagFilename)
+	return restoreFile(v.copyRangeMethod, v.versionsFs, v.folderFs, filepath, versionTime, TagFilename)
 }
 
 func (v *staggered) String() string {

lib/versioner/staggered_test.go

@@ -7,6 +7,7 @@
 package versioner
 
 import (
+	"github.com/syncthing/syncthing/lib/config"
 	"sort"
 	"strconv"
 	"testing"
@@ -96,9 +97,17 @@ func TestStaggeredVersioningVersionCount(t *testing.T) {
 	}
 	sort.Strings(delete)
 
-	v := newStaggered(fs.NewFilesystem(fs.FilesystemTypeFake, "testdata"), map[string]string{
-		"maxAge": strconv.Itoa(365 * 86400),
-	}).(*staggered)
+	cfg := config.FolderConfiguration{
+		FilesystemType: fs.FilesystemTypeBasic,
+		Path:           "testdata",
+		Versioning: config.VersioningConfiguration{
+			Params: map[string]string{
+				"maxAge": strconv.Itoa(365 * 86400),
+			},
+		},
+	}
+
+	v := newStaggered(cfg).(*staggered)
 	rem := v.toRemove(versionsWithMtime, now)
 	sort.Strings(rem)
 

lib/versioner/trashcan.go

@@ -14,6 +14,7 @@ import (
 
 	"github.com/thejerf/suture"
 
+	"github.com/syncthing/syncthing/lib/config"
 	"github.com/syncthing/syncthing/lib/fs"
 	"github.com/syncthing/syncthing/lib/util"
 )
@@ -25,19 +26,21 @@ func init() {
 
 type trashcan struct {
 	suture.Service
-	folderFs     fs.Filesystem
-	versionsFs   fs.Filesystem
-	cleanoutDays int
+	folderFs        fs.Filesystem
+	versionsFs      fs.Filesystem
+	cleanoutDays    int
+	copyRangeMethod fs.CopyRangeMethod
 }
 
-func newTrashcan(folderFs fs.Filesystem, params map[string]string) Versioner {
-	cleanoutDays, _ := strconv.Atoi(params["cleanoutDays"])
+func newTrashcan(cfg config.FolderConfiguration) Versioner {
+	cleanoutDays, _ := strconv.Atoi(cfg.Versioning.Params["cleanoutDays"])
 	// On error we default to 0, "do not clean out the trash can"
 
 	s := &trashcan{
-		folderFs:     folderFs,
-		versionsFs:   fsFromParams(folderFs, params),
-		cleanoutDays: cleanoutDays,
+		folderFs:        cfg.Filesystem(),
+		versionsFs:      versionerFsFromFolderCfg(cfg),
+		cleanoutDays:    cleanoutDays,
+		copyRangeMethod: cfg.CopyRangeMethod,
 	}
 	s.Service = util.AsService(s.serve, s.String())
 
@@ -48,7 +51,7 @@ func newTrashcan(folderFs fs.Filesystem, params map[string]string) Versioner {
 // Archive moves the named file away to a version archive. If this function
 // returns nil, the named file does not exist any more (has been archived).
 func (t *trashcan) Archive(filePath string) error {
-	return archiveFile(t.folderFs, t.versionsFs, filePath, func(name, tag string) string {
+	return archiveFile(t.copyRangeMethod, t.folderFs, t.versionsFs, filePath, func(name, tag string) string {
 		return name
 	})
 }
@@ -144,7 +147,7 @@ func (t *trashcan) Restore(filepath string, versionTime time.Time) error {
 		return name
 	}
 
-	err := restoreFile(t.versionsFs, t.folderFs, filepath, versionTime, tagger)
+	err := restoreFile(t.copyRangeMethod, t.versionsFs, t.folderFs, filepath, versionTime, tagger)
 	if taggedName == "" {
 		return err
 	}

lib/versioner/trashcan_test.go

@@ -7,6 +7,7 @@
 package versioner
 
 import (
+	"github.com/syncthing/syncthing/lib/config"
 	"io/ioutil"
 	"os"
 	"path/filepath"
@@ -53,7 +54,17 @@ func TestTrashcanCleanout(t *testing.T) {
 		}
 	}
 
-	versioner := newTrashcan(fs.NewFilesystem(fs.FilesystemTypeBasic, "testdata"), map[string]string{"cleanoutDays": "7"}).(*trashcan)
+	cfg := config.FolderConfiguration{
+		FilesystemType: fs.FilesystemTypeBasic,
+		Path:           "testdata",
+		Versioning: config.VersioningConfiguration{
+			Params: map[string]string{
+				"cleanoutDays": "7",
+			},
+		},
+	}
+
+	versioner := newTrashcan(cfg).(*trashcan)
 	if err := versioner.cleanoutArchive(); err != nil {
 		t.Fatal(err)
 	}
@@ -90,15 +101,23 @@ func TestTrashcanArchiveRestoreSwitcharoo(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	folderFs := fs.NewFilesystem(fs.FilesystemTypeBasic, tmpDir1)
+	cfg := config.FolderConfiguration{
+		FilesystemType: fs.FilesystemTypeBasic,
+		Path:           tmpDir1,
+		Versioning: config.VersioningConfiguration{
+			Params: map[string]string{
+				"fsType": "basic",
+				"fsPath": tmpDir2,
+			},
+		},
+	}
+	folderFs := cfg.Filesystem()
+
 	versionsFs := fs.NewFilesystem(fs.FilesystemTypeBasic, tmpDir2)
 
 	writeFile(t, folderFs, "file", "A")
 
-	versioner := newTrashcan(folderFs, map[string]string{
-		"fsType": "basic",
-		"fsPath": tmpDir2,
-	})
+	versioner := newTrashcan(cfg)
 
 	if err := versioner.Archive("file"); err != nil {
 		t.Fatal(err)

lib/versioner/util.go

@@ -14,6 +14,8 @@ import (
 	"time"
 
 	"github.com/pkg/errors"
+
+	"github.com/syncthing/syncthing/lib/config"
 	"github.com/syncthing/syncthing/lib/fs"
 	"github.com/syncthing/syncthing/lib/osutil"
 	"github.com/syncthing/syncthing/lib/util"
@@ -129,7 +131,7 @@ func retrieveVersions(fileSystem fs.Filesystem) (map[string][]FileVersion, error
 
 type fileTagger func(string, string) string
 
-func archiveFile(srcFs, dstFs fs.Filesystem, filePath string, tagger fileTagger) error {
+func archiveFile(method fs.CopyRangeMethod, srcFs, dstFs fs.Filesystem, filePath string, tagger fileTagger) error {
 	filePath = osutil.NativeFilename(filePath)
 	info, err := srcFs.Lstat(filePath)
 	if fs.IsNotExist(err) {
@@ -170,7 +172,7 @@ func archiveFile(srcFs, dstFs fs.Filesystem, filePath string, tagger fileTagger)
 	ver := tagger(file, now.Format(TimeFormat))
 	dst := filepath.Join(inFolderPath, ver)
 	l.Debugln("archiving", filePath, "moving to", dst)
-	err = osutil.RenameOrCopy(srcFs, dstFs, filePath, dst)
+	err = osutil.RenameOrCopy(method, srcFs, dstFs, filePath, dst)
 
 	mtime := info.ModTime()
 	// If it's a trashcan versioner type thing, then it does not have version time in the name
@@ -184,7 +186,7 @@ func archiveFile(srcFs, dstFs fs.Filesystem, filePath string, tagger fileTagger)
 	return err
 }
 
-func restoreFile(src, dst fs.Filesystem, filePath string, versionTime time.Time, tagger fileTagger) error {
+func restoreFile(method fs.CopyRangeMethod, src, dst fs.Filesystem, filePath string, versionTime time.Time, tagger fileTagger) error {
 	tag := versionTime.In(time.Local).Truncate(time.Second).Format(TimeFormat)
 	taggedFilePath := tagger(filePath, tag)
 
@@ -200,7 +202,7 @@ func restoreFile(src, dst fs.Filesystem, filePath string, versionTime time.Time,
 				return errors.Wrap(err, "removing existing symlink")
 			}
 		case info.IsRegular():
-			if err := archiveFile(dst, src, filePath, tagger); err != nil {
+			if err := archiveFile(method, dst, src, filePath, tagger); err != nil {
 				return errors.Wrap(err, "archiving existing file")
 			}
 		default:
@@ -247,12 +249,14 @@ func restoreFile(src, dst fs.Filesystem, filePath string, versionTime time.Time,
 	}
 
 	_ = dst.MkdirAll(filepath.Dir(filePath), 0755)
-	err := osutil.RenameOrCopy(src, dst, sourceFile, filePath)
+	err := osutil.RenameOrCopy(method, src, dst, sourceFile, filePath)
 	_ = dst.Chtimes(filePath, sourceMtime, sourceMtime)
 	return err
 }
 
-func fsFromParams(folderFs fs.Filesystem, params map[string]string) (versionsFs fs.Filesystem) {
+func versionerFsFromFolderCfg(cfg config.FolderConfiguration) (versionsFs fs.Filesystem) {
+	params := cfg.Versioning.Params
+	folderFs := cfg.Filesystem()
 	if params["fsType"] == "" && params["fsPath"] == "" {
 		versionsFs = fs.NewFilesystem(folderFs.Type(), filepath.Join(folderFs.URI(), ".stversions"))
 

lib/versioner/versioner.go

@@ -14,7 +14,6 @@ import (
 	"time"
 
 	"github.com/syncthing/syncthing/lib/config"
-	"github.com/syncthing/syncthing/lib/fs"
 )
 
 type Versioner interface {
@@ -29,7 +28,7 @@ type FileVersion struct {
 	Size        int64     `json:"size"`
 }
 
-type factory func(filesystem fs.Filesystem, params map[string]string) Versioner
+type factory func(cfg config.FolderConfiguration) Versioner
 
 var factories = make(map[string]factory)
 
@@ -40,11 +39,11 @@ const (
 	timeGlob   = "[0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9]-[0-9][0-9][0-9][0-9][0-9][0-9]" // glob pattern matching TimeFormat
 )
 
-func New(fs fs.Filesystem, cfg config.VersioningConfiguration) (Versioner, error) {
-	fac, ok := factories[cfg.Type]
+func New(cfg config.FolderConfiguration) (Versioner, error) {
+	fac, ok := factories[cfg.Versioning.Type]
 	if !ok {
 		return nil, fmt.Errorf("requested versioning type %q does not exist", cfg.Type)
 	}
 
-	return fac(fs, cfg.Params), nil
+	return fac(cfg), nil
 }