lib/model: Improve scan scheduling and dir del during pull (fixes #4475 #4476)

GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/4493

lib/model/model_test.go

@@ -2121,39 +2121,6 @@ func TestIssue3028(t *testing.T) {
 	}
 }
 
-func TestIssue3164(t *testing.T) {
-	os.RemoveAll("testdata/issue3164")
-	defer os.RemoveAll("testdata/issue3164")
-
-	if err := os.MkdirAll("testdata/issue3164/oktodelete/foobar", 0777); err != nil {
-		t.Fatal(err)
-	}
-	if err := ioutil.WriteFile("testdata/issue3164/oktodelete/foobar/file", []byte("Hello"), 0644); err != nil {
-		t.Fatal(err)
-	}
-	if err := ioutil.WriteFile("testdata/issue3164/oktodelete/file", []byte("Hello"), 0644); err != nil {
-		t.Fatal(err)
-	}
-	f := protocol.FileInfo{
-		Name: "issue3164",
-	}
-	m := ignore.New(defaultFs)
-	if err := m.Parse(bytes.NewBufferString("(?d)oktodelete"), ""); err != nil {
-		t.Fatal(err)
-	}
-
-	fl := sendReceiveFolder{
-		dbUpdates: make(chan dbUpdateJob, 1),
-		fs:        fs.NewFilesystem(fs.FilesystemTypeBasic, "testdata"),
-	}
-
-	fl.deleteDir(f, m)
-
-	if _, err := os.Stat("testdata/issue3164"); !os.IsNotExist(err) {
-		t.Fatal(err)
-	}
-}
-
 func TestIssue4357(t *testing.T) {
 	db := db.OpenMemory()
 	cfg := defaultConfig.RawCopy()
@@ -2761,6 +2728,147 @@ func TestCustomMarkerName(t *testing.T) {
 	}
 }
 
+func TestRemoveDirWithContent(t *testing.T) {
+	defer func() {
+		defaultFs.RemoveAll("dirwith")
+	}()
+
+	defaultFs.MkdirAll("dirwith", 0755)
+	content := filepath.Join("dirwith", "content")
+	fd, err := defaultFs.Create(content)
+	if err != nil {
+		t.Fatal(err)
+		return
+	}
+	fd.Close()
+
+	dbi := db.OpenMemory()
+	m := NewModel(defaultConfig, protocol.LocalDeviceID, "syncthing", "dev", dbi, nil)
+	m.AddFolder(defaultFolderConfig)
+	m.StartFolder("default")
+	m.ServeBackground()
+	defer m.Stop()
+	m.ScanFolder("default")
+
+	dir, ok := m.CurrentFolderFile("default", "dirwith")
+	if !ok {
+		t.Fatalf("Can't get dir \"dirwith\" after initial scan")
+	}
+	dir.Deleted = true
+	dir.Version = dir.Version.Update(device1.Short()).Update(device1.Short())
+
+	file, ok := m.CurrentFolderFile("default", content)
+	if !ok {
+		t.Fatalf("Can't get file \"%v\" after initial scan", content)
+	}
+	file.Deleted = true
+	file.Version = file.Version.Update(device1.Short()).Update(device1.Short())
+
+	m.IndexUpdate(device1, "default", []protocol.FileInfo{dir, file})
+
+	// Is there something we could trigger on instead of just waiting?
+	timeout := time.NewTimer(5 * time.Second)
+	for {
+		dir, ok := m.CurrentFolderFile("default", "dirwith")
+		if !ok {
+			t.Fatalf("Can't get dir \"dirwith\" after index update")
+		}
+		file, ok := m.CurrentFolderFile("default", content)
+		if !ok {
+			t.Fatalf("Can't get file \"%v\" after index update", content)
+		}
+		if dir.Deleted && file.Deleted {
+			return
+		}
+
+		select {
+		case <-timeout.C:
+			if !dir.Deleted && !file.Deleted {
+				t.Errorf("Neither the dir nor its content was deleted before timing out.")
+			} else if !dir.Deleted {
+				t.Errorf("The dir was not deleted before timing out.")
+			} else {
+				t.Errorf("The content of the dir was not deleted before timing out.")
+			}
+			return
+		default:
+			time.Sleep(100 * time.Millisecond)
+		}
+	}
+}
+
+func TestIssue4475(t *testing.T) {
+	defer func() {
+		defaultFs.RemoveAll("delDir")
+	}()
+
+	err := defaultFs.MkdirAll("delDir", 0755)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	dbi := db.OpenMemory()
+	m := NewModel(defaultConfig, protocol.LocalDeviceID, "syncthing", "dev", dbi, nil)
+	m.AddFolder(defaultFolderConfig)
+	m.StartFolder("default")
+	m.ServeBackground()
+	defer m.Stop()
+	m.ScanFolder("default")
+
+	// Scenario: Dir is deleted locally and before syncing/index exchange
+	// happens, a file is create in that dir on the remote.
+	// This should result in the directory being recreated and added to the
+	// db locally.
+
+	if err = defaultFs.RemoveAll("delDir"); err != nil {
+		t.Fatal(err)
+	}
+
+	m.ScanFolder("default")
+
+	conn := addFakeConn(m, device1)
+	conn.folder = "default"
+
+	if !m.folderSharedWith("default", device1) {
+		t.Fatal("not shared with device1")
+	}
+
+	fileName := filepath.Join("delDir", "file")
+	conn.addFile(fileName, 0644, protocol.FileInfoTypeFile, nil)
+	conn.sendIndexUpdate()
+
+	// Is there something we could trigger on instead of just waiting?
+	timeout := time.NewTimer(5 * time.Second)
+	created := false
+	for {
+		if !created {
+			if _, ok := m.CurrentFolderFile("default", fileName); ok {
+				created = true
+			}
+		} else {
+			dir, ok := m.CurrentFolderFile("default", "delDir")
+			if !ok {
+				t.Fatalf("can't get dir from db")
+			}
+			if !dir.Deleted {
+				return
+			}
+		}
+
+		select {
+		case <-timeout.C:
+			if created {
+				t.Errorf("Timed out before file from remote was created")
+			} else {
+				t.Errorf("Timed out before directory was resurrected in db")
+			}
+			return
+		default:
+			time.Sleep(100 * time.Millisecond)
+		}
+	}
+}
+
 func addFakeConn(m *Model, dev protocol.DeviceID) *fakeConnection {
 	fc := &fakeConnection{id: dev, model: m}
 	m.AddConnection(fc, protocol.HelloResult{})

lib/model/rwfolder.go

@@ -60,6 +60,9 @@ var (
 	activity               = newDeviceActivity()
 	errNoDevice            = errors.New("peers who had this file went away, or the file has changed while syncing. will retry later")
 	errSymlinksUnsupported = errors.New("symlinks not supported")
+	errDirHasToBeScanned   = errors.New("directory contains unexpected files, scheduling scan")
+	errDirHasIgnored       = errors.New("directory contains ignored files (see ignore documentation for (?d) prefix)")
+	errDirNotEmpty         = errors.New("directory is not empty")
 )
 
 const (
@@ -92,7 +95,6 @@ type sendReceiveFolder struct {
 	pause     time.Duration
 
 	queue         *jobQueue
-	dbUpdates     chan dbUpdateJob
 	pullScheduled chan struct{}
 
 	errors    map[string]string // path -> error string
@@ -255,13 +257,17 @@ func (f *sendReceiveFolder) pull(prevIgnoreHash string) (curIgnoreHash string, s
 
 	f.setState(FolderSyncing)
 	f.clearErrors()
+
+	scanChan := make(chan string)
+	go f.pullScannerRoutine(scanChan)
+
 	var changed int
 	tries := 0
 
 	for {
 		tries++
 
-		changed := f.pullerIteration(curIgnores, ignoresChanged)
+		changed = f.pullerIteration(curIgnores, ignoresChanged, scanChan)
 		l.Debugln(f, "changed", changed)
 
 		if changed == 0 {
@@ -294,6 +300,8 @@ func (f *sendReceiveFolder) pull(prevIgnoreHash string) (curIgnoreHash string, s
 
 	f.setState(FolderIdle)
 
+	close(scanChan)
+
 	if changed == 0 {
 		return curIgnoreHash, true
 	}
@@ -305,23 +313,23 @@ func (f *sendReceiveFolder) pull(prevIgnoreHash string) (curIgnoreHash string, s
 // returns the number items that should have been synced (even those that
 // might have failed). One puller iteration handles all files currently
 // flagged as needed in the folder.
-func (f *sendReceiveFolder) pullerIteration(ignores *ignore.Matcher, ignoresChanged bool) int {
+func (f *sendReceiveFolder) pullerIteration(ignores *ignore.Matcher, ignoresChanged bool, scanChan chan<- string) int {
 	pullChan := make(chan pullBlockState)
 	copyChan := make(chan copyBlocksState)
 	finisherChan := make(chan *sharedPullerState)
+	dbUpdateChan := make(chan dbUpdateJob)
 
-	updateWg := sync.NewWaitGroup()
-	copyWg := sync.NewWaitGroup()
 	pullWg := sync.NewWaitGroup()
+	copyWg := sync.NewWaitGroup()
 	doneWg := sync.NewWaitGroup()
+	updateWg := sync.NewWaitGroup()
 
 	l.Debugln(f, "c", f.Copiers, "p", f.Pullers)
 
-	f.dbUpdates = make(chan dbUpdateJob)
 	updateWg.Add(1)
 	go func() {
-		// dbUpdaterRoutine finishes when f.dbUpdates is closed
+		// dbUpdaterRoutine finishes when dbUpdateChan is closed
-		f.dbUpdaterRoutine()
+		f.dbUpdaterRoutine(dbUpdateChan)
 		updateWg.Done()
 	}()
 
@@ -346,7 +354,7 @@ func (f *sendReceiveFolder) pullerIteration(ignores *ignore.Matcher, ignoresChan
 	doneWg.Add(1)
 	// finisherRoutine finishes when finisherChan is closed
 	go func() {
-		f.finisherRoutine(finisherChan)
+		f.finisherRoutine(ignores, finisherChan, dbUpdateChan, scanChan)
 		doneWg.Done()
 	}()
 
@@ -388,7 +396,7 @@ func (f *sendReceiveFolder) pullerIteration(ignores *ignore.Matcher, ignoresChan
 		case ignores.ShouldIgnore(file.Name):
 			file.Invalidate(f.model.id.Short())
 			l.Debugln(f, "Handling ignored file", file)
-			f.dbUpdates <- dbUpdateJob{file, dbUpdateInvalidate}
+			dbUpdateChan <- dbUpdateJob{file, dbUpdateInvalidate}
 
 		case file.IsDeleted():
 			processDirectly = append(processDirectly, file)
@@ -411,7 +419,7 @@ func (f *sendReceiveFolder) pullerIteration(ignores *ignore.Matcher, ignoresChan
 		case runtime.GOOS == "windows" && file.IsSymlink():
 			file.Invalidate(f.model.id.Short())
 			l.Debugln(f, "Invalidating symlink (unsupported)", file.Name)
-			f.dbUpdates <- dbUpdateJob{file, dbUpdateInvalidate}
+			dbUpdateChan <- dbUpdateJob{file, dbUpdateInvalidate}
 
 		default:
 			// Directories, symlinks
@@ -464,11 +472,12 @@ func (f *sendReceiveFolder) pullerIteration(ignores *ignore.Matcher, ignoresChan
 
 		case fi.IsDirectory() && !fi.IsSymlink():
 			l.Debugln(f, "Handling directory", fi.Name)
-			f.handleDir(fi)
+			f.handleDir(fi, dbUpdateChan)
 
 		case fi.IsSymlink():
+			l.Debugln("Handling symlink", fi.Name)
 			l.Debugln(f, "Handling symlink", fi.Name)
-			f.handleSymlink(fi)
+			f.handleSymlink(fi, dbUpdateChan)
 
 		default:
 			l.Warnln(fi)
@@ -523,13 +532,33 @@ nextFile:
 			continue
 		}
 
+		dirName := filepath.Dir(fi.Name)
+
 		// Verify that the thing we are handling lives inside a directory,
 		// and not a symlink or empty space.
-		if err := osutil.TraversesSymlink(f.fs, filepath.Dir(fi.Name)); err != nil {
+		if err := osutil.TraversesSymlink(f.fs, dirName); err != nil {
 			f.newError("traverses q", fi.Name, err)
 			continue
 		}
 
+		// issues #114 and #4475: This works around a race condition
+		// between two devices, when one device removes a directory and the
+		// other creates a file in it. However that happens, we end up with
+		// a directory for "foo" with the delete bit, but a file "foo/bar"
+		// that we want to sync. We never create the directory, and hence
+		// fail to create the file and end up looping forever on it. This
+		// breaks that by creating the directory and scheduling a scan,
+		// where it will be found and the delete bit on it removed.  The
+		// user can then clean up as they like...
+		if _, err := f.fs.Lstat(dirName); fs.IsNotExist(err) {
+			l.Debugln("%v resurrecting parent directory of %v", f, fi.Name)
+			if err := f.fs.MkdirAll(dirName, 0755); err != nil {
+				f.newError("resurrecting parent dir", fi.Name, err)
+				continue
+			}
+			scanChan <- dirName
+		}
+
 		// Check our list of files to be removed for a match, in which case
 		// we can just do a rename instead.
 		key := string(fi.Blocks[0].Hash)
@@ -547,7 +576,7 @@ nextFile:
 				// Remove the pending deletion (as we perform it by renaming)
 				delete(fileDeletions, candidate.Name)
 
-				f.renameFile(desired, fi)
+				f.renameFile(desired, fi, dbUpdateChan)
 
 				f.queue.Done(fileName)
 				continue nextFile
@@ -555,7 +584,7 @@ nextFile:
 		}
 
 		// Handle the file normally, by coping and pulling, etc.
-		f.handleFile(fi, copyChan, finisherChan)
+		f.handleFile(fi, copyChan, finisherChan, dbUpdateChan)
 	}
 
 	// Signal copy and puller routines that we are done with the in data for
@@ -573,24 +602,24 @@ nextFile:
 
 	for _, file := range fileDeletions {
 		l.Debugln(f, "Deleting file", file.Name)
-		f.deleteFile(file)
+		f.deleteFile(file, dbUpdateChan)
 	}
 
 	for i := range dirDeletions {
 		dir := dirDeletions[len(dirDeletions)-i-1]
 		l.Debugln(f, "Deleting dir", dir.Name)
-		f.deleteDir(dir, ignores)
+		f.handleDeleteDir(dir, ignores, dbUpdateChan, scanChan)
 	}
 
-	// Wait for db updates to complete
+	// Wait for db updates and scan scheduling to complete
-	close(f.dbUpdates)
+	close(dbUpdateChan)
 	updateWg.Wait()
 
 	return changed
 }
 
 // handleDir creates or updates the given directory
-func (f *sendReceiveFolder) handleDir(file protocol.FileInfo) {
+func (f *sendReceiveFolder) handleDir(file protocol.FileInfo, dbUpdateChan chan<- dbUpdateJob) {
 	// Used in the defer closure below, updated by the function body. Take
 	// care not declare another err.
 	var err error
@@ -658,7 +687,7 @@ func (f *sendReceiveFolder) handleDir(file protocol.FileInfo) {
 		}
 
 		if err = osutil.InWritableDir(mkdir, f.fs, file.Name); err == nil {
-			f.dbUpdates <- dbUpdateJob{file, dbUpdateHandleDir}
+			dbUpdateChan <- dbUpdateJob{file, dbUpdateHandleDir}
 		} else {
 			f.newError("dir mkdir", file.Name, err)
 		}
@@ -674,16 +703,16 @@ func (f *sendReceiveFolder) handleDir(file protocol.FileInfo) {
 	// don't handle modification times on directories, because that sucks...)
 	// It's OK to change mode bits on stuff within non-writable directories.
 	if f.ignorePermissions(file) {
-		f.dbUpdates <- dbUpdateJob{file, dbUpdateHandleDir}
+		dbUpdateChan <- dbUpdateJob{file, dbUpdateHandleDir}
 	} else if err := f.fs.Chmod(file.Name, mode|(fs.FileMode(info.Mode())&retainBits)); err == nil {
-		f.dbUpdates <- dbUpdateJob{file, dbUpdateHandleDir}
+		dbUpdateChan <- dbUpdateJob{file, dbUpdateHandleDir}
 	} else {
 		f.newError("dir chmod", file.Name, err)
 	}
 }
 
 // handleSymlink creates or updates the given symlink
-func (f *sendReceiveFolder) handleSymlink(file protocol.FileInfo) {
+func (f *sendReceiveFolder) handleSymlink(file protocol.FileInfo, dbUpdateChan chan<- dbUpdateJob) {
 	// Used in the defer closure below, updated by the function body. Take
 	// care not declare another err.
 	var err error
@@ -736,14 +765,14 @@ func (f *sendReceiveFolder) handleSymlink(file protocol.FileInfo) {
 	}
 
 	if err = osutil.InWritableDir(createLink, f.fs, file.Name); err == nil {
-		f.dbUpdates <- dbUpdateJob{file, dbUpdateHandleSymlink}
+		dbUpdateChan <- dbUpdateJob{file, dbUpdateHandleSymlink}
 	} else {
 		f.newError("symlink create", file.Name, err)
 	}
 }
 
-// deleteDir attempts to delete the given directory
+// handleDeleteDir attempts to remove a directory that was deleted on a remote
-func (f *sendReceiveFolder) deleteDir(file protocol.FileInfo, matcher *ignore.Matcher) {
+func (f *sendReceiveFolder) handleDeleteDir(file protocol.FileInfo, ignores *ignore.Matcher, dbUpdateChan chan<- dbUpdateJob, scanChan chan<- string) {
 	// Used in the defer closure below, updated by the function body. Take
 	// care not declare another err.
 	var err error
@@ -765,33 +794,18 @@ func (f *sendReceiveFolder) deleteDir(file protocol.FileInfo, matcher *ignore.Ma
 		})
 	}()
 
-	// Delete any temporary files lying around in the directory
+	err = f.deleteDir(file.Name, ignores, scanChan)
 
-	files, _ := f.fs.DirNames(file.Name)
+	if err != nil {
-	for _, dirFile := range files {
-		fullDirFile := filepath.Join(file.Name, dirFile)
-		if fs.IsTemporary(dirFile) || (matcher != nil && matcher.Match(fullDirFile).IsDeletable()) {
-			f.fs.RemoveAll(fullDirFile)
-		}
-	}
-
-	err = osutil.InWritableDir(f.fs.Remove, f.fs, file.Name)
-	if err == nil || fs.IsNotExist(err) {
-		// It was removed or it doesn't exist to start with
-		f.dbUpdates <- dbUpdateJob{file, dbUpdateDeleteDir}
-	} else if _, serr := f.fs.Lstat(file.Name); serr != nil && !fs.IsPermission(serr) {
-		// We get an error just looking at the directory, and it's not a
-		// permission problem. Lets assume the error is in fact some variant
-		// of "file does not exist" (possibly expressed as some parent being a
-		// file and not a directory etc) and that the delete is handled.
-		f.dbUpdates <- dbUpdateJob{file, dbUpdateDeleteDir}
-	} else {
 		f.newError("delete dir", file.Name, err)
+		return
 	}
+
+	dbUpdateChan <- dbUpdateJob{file, dbUpdateDeleteDir}
 }
 
 // deleteFile attempts to delete the given file
-func (f *sendReceiveFolder) deleteFile(file protocol.FileInfo) {
+func (f *sendReceiveFolder) deleteFile(file protocol.FileInfo, dbUpdateChan chan<- dbUpdateJob) {
 	// Used in the defer closure below, updated by the function body. Take
 	// care not declare another err.
 	var err error
@@ -830,13 +844,13 @@ func (f *sendReceiveFolder) deleteFile(file protocol.FileInfo) {
 
 	if err == nil || fs.IsNotExist(err) {
 		// It was removed or it doesn't exist to start with
-		f.dbUpdates <- dbUpdateJob{file, dbUpdateDeleteFile}
+		dbUpdateChan <- dbUpdateJob{file, dbUpdateDeleteFile}
 	} else if _, serr := f.fs.Lstat(file.Name); serr != nil && !fs.IsPermission(serr) {
 		// We get an error just looking at the file, and it's not a permission
 		// problem. Lets assume the error is in fact some variant of "file
 		// does not exist" (possibly expressed as some parent being a file and
 		// not a directory etc) and that the delete is handled.
-		f.dbUpdates <- dbUpdateJob{file, dbUpdateDeleteFile}
+		dbUpdateChan <- dbUpdateJob{file, dbUpdateDeleteFile}
 	} else {
 		f.newError("delete file", file.Name, err)
 	}
@@ -844,7 +858,7 @@ func (f *sendReceiveFolder) deleteFile(file protocol.FileInfo) {
 
 // renameFile attempts to rename an existing file to a destination
 // and set the right attributes on it.
-func (f *sendReceiveFolder) renameFile(source, target protocol.FileInfo) {
+func (f *sendReceiveFolder) renameFile(source, target protocol.FileInfo, dbUpdateChan chan<- dbUpdateJob) {
 	// Used in the defer closure below, updated by the function body. Take
 	// care not declare another err.
 	var err error
@@ -900,7 +914,7 @@ func (f *sendReceiveFolder) renameFile(source, target protocol.FileInfo) {
 		// of the source and the creation of the target. Fix-up the metadata,
 		// and update the local index of the target file.
 
-		f.dbUpdates <- dbUpdateJob{source, dbUpdateDeleteFile}
+		dbUpdateChan <- dbUpdateJob{source, dbUpdateDeleteFile}
 
 		err = f.shortcutFile(target)
 		if err != nil {
@@ -909,7 +923,7 @@ func (f *sendReceiveFolder) renameFile(source, target protocol.FileInfo) {
 			return
 		}
 
-		f.dbUpdates <- dbUpdateJob{target, dbUpdateHandleFile}
+		dbUpdateChan <- dbUpdateJob{target, dbUpdateHandleFile}
 	} else {
 		// We failed the rename so we have a source file that we still need to
 		// get rid of. Attempt to delete it instead so that we make *some*
@@ -922,7 +936,7 @@ func (f *sendReceiveFolder) renameFile(source, target protocol.FileInfo) {
 			return
 		}
 
-		f.dbUpdates <- dbUpdateJob{source, dbUpdateDeleteFile}
+		dbUpdateChan <- dbUpdateJob{source, dbUpdateDeleteFile}
 	}
 }
 
@@ -962,7 +976,7 @@ func (f *sendReceiveFolder) renameFile(source, target protocol.FileInfo) {
 
 // handleFile queues the copies and pulls as necessary for a single new or
 // changed file.
-func (f *sendReceiveFolder) handleFile(file protocol.FileInfo, copyChan chan<- copyBlocksState, finisherChan chan<- *sharedPullerState) {
+func (f *sendReceiveFolder) handleFile(file protocol.FileInfo, copyChan chan<- copyBlocksState, finisherChan chan<- *sharedPullerState, dbUpdateChan chan<- dbUpdateJob) {
 	curFile, hasCurFile := f.model.CurrentFolderFile(f.folderID, file.Name)
 
 	have, need := scanner.BlockDiff(curFile.Blocks, file.Blocks)
@@ -994,7 +1008,7 @@ func (f *sendReceiveFolder) handleFile(file protocol.FileInfo, copyChan chan<- c
 		if err != nil {
 			f.newError("shortcut", file.Name, err)
 		} else {
-			f.dbUpdates <- dbUpdateJob{file, dbUpdateShortcutFile}
+			dbUpdateChan <- dbUpdateJob{file, dbUpdateShortcutFile}
 		}
 
 		return
@@ -1353,7 +1367,7 @@ func (f *sendReceiveFolder) pullerRoutine(in <-chan pullBlockState, out chan<- *
 	}
 }
 
-func (f *sendReceiveFolder) performFinish(state *sharedPullerState) error {
+func (f *sendReceiveFolder) performFinish(ignores *ignore.Matcher, state *sharedPullerState, dbUpdateChan chan<- dbUpdateJob, scanChan chan<- string) error {
 	// Set the correct permission bits on the new file
 	if !f.ignorePermissions(state.file) {
 		if err := f.fs.Chmod(state.tempName, fs.FileMode(state.file.Permissions&0777)); err != nil {
@@ -1407,14 +1421,7 @@ func (f *sendReceiveFolder) performFinish(state *sharedPullerState) error {
 		}
 
 		if changed {
-			// Scan() is synchronous (i.e. blocks until the scan is
+			scanChan <- state.curFile.Name
-			// completed and returns an error), but a scan can't happen
-			// while we're in the puller routine. Request the scan in the
-			// background and it'll be handled when the current pulling
-			// sweep is complete. As we do retries, we'll queue the scan
-			// for this file up to ten times, but the last nine of those
-			// scans will be cheap...
-			go f.Scan([]string{state.curFile.Name})
 			return fmt.Errorf("file modified but not rescanned; will try again later")
 		}
 
@@ -1424,11 +1431,7 @@ func (f *sendReceiveFolder) performFinish(state *sharedPullerState) error {
 			// archived for conflicts, only removed (which of course fails for
 			// non-empty directories).
 
-			// TODO: This is the place where we want to remove temporary files
+			if err = f.deleteDir(state.file.Name, ignores, scanChan); err != nil {
-			// and future hard ignores before attempting a directory delete.
-			// Should share code with f.deletDir().
-
-			if err = osutil.InWritableDir(f.fs.Remove, f.fs, state.file.Name); err != nil {
 				return err
 			}
 
@@ -1467,11 +1470,11 @@ func (f *sendReceiveFolder) performFinish(state *sharedPullerState) error {
 	f.fs.Chtimes(state.file.Name, state.file.ModTime(), state.file.ModTime()) // never fails
 
 	// Record the updated file in the index
-	f.dbUpdates <- dbUpdateJob{state.file, dbUpdateHandleFile}
+	dbUpdateChan <- dbUpdateJob{state.file, dbUpdateHandleFile}
 	return nil
 }
 
-func (f *sendReceiveFolder) finisherRoutine(in <-chan *sharedPullerState) {
+func (f *sendReceiveFolder) finisherRoutine(ignores *ignore.Matcher, in <-chan *sharedPullerState, dbUpdateChan chan<- dbUpdateJob, scanChan chan<- string) {
 	for state := range in {
 		if closed, err := state.finalClose(); closed {
 			l.Debugln(f, "closing", state.file.Name)
@@ -1479,7 +1482,7 @@ func (f *sendReceiveFolder) finisherRoutine(in <-chan *sharedPullerState) {
 			f.queue.Done(state.file.Name)
 
 			if err == nil {
-				err = f.performFinish(state)
+				err = f.performFinish(ignores, state, dbUpdateChan, scanChan)
 			}
 
 			if err != nil {
@@ -1523,7 +1526,7 @@ func (f *sendReceiveFolder) Jobs() ([]string, []string) {
 
 // dbUpdaterRoutine aggregates db updates and commits them in batches no
 // larger than 1000 items, and no more delayed than 2 seconds.
-func (f *sendReceiveFolder) dbUpdaterRoutine() {
+func (f *sendReceiveFolder) dbUpdaterRoutine(dbUpdateChan <-chan dbUpdateJob) {
 	const maxBatchTime = 2 * time.Second
 
 	batch := make([]dbUpdateJob, 0, maxBatchSizeFiles)
@@ -1592,7 +1595,7 @@ func (f *sendReceiveFolder) dbUpdaterRoutine() {
 loop:
 	for {
 		select {
-		case job, ok := <-f.dbUpdates:
+		case job, ok := <-dbUpdateChan:
 			if !ok {
 				break loop
 			}
@@ -1619,6 +1622,25 @@ loop:
 	}
 }
 
+// pullScannerRoutine aggregates paths to be scanned after pulling. The scan is
+// scheduled once when scanChan is closed (scanning can not happen during pulling).
+func (f *sendReceiveFolder) pullScannerRoutine(scanChan <-chan string) {
+	toBeScanned := make(map[string]struct{})
+
+	for path := range scanChan {
+		toBeScanned[path] = struct{}{}
+	}
+
+	if len(toBeScanned) != 0 {
+		scanList := make([]string, 0, len(toBeScanned))
+		for path := range toBeScanned {
+			l.Debugln(f, "scheduling scan after pulling for", path)
+			scanList = append(scanList, path)
+		}
+		f.Scan(scanList)
+	}
+}
+
 func (f *sendReceiveFolder) inConflict(current, replacement protocol.Vector) bool {
 	if current.Concurrent(replacement) {
 		// Obvious case
@@ -1732,6 +1754,66 @@ func (f *sendReceiveFolder) IgnoresUpdated() {
 	f.SchedulePull()
 }
 
+// deleteDir attempts to delete a directory. It checks for files/dirs inside
+// the directory and removes them if possible or returns an error if it fails
+func (f *sendReceiveFolder) deleteDir(dir string, ignores *ignore.Matcher, scanChan chan<- string) error {
+	files, _ := f.fs.DirNames(dir)
+
+	toBeDeleted := make([]string, 0, len(files))
+
+	hasIgnored := false
+	hasKnown := false
+	hasToBeScanned := false
+
+	for _, dirFile := range files {
+		fullDirFile := filepath.Join(dir, dirFile)
+		if fs.IsTemporary(dirFile) || ignores.Match(fullDirFile).IsDeletable() {
+			toBeDeleted = append(toBeDeleted, fullDirFile)
+		} else if ignores != nil && ignores.Match(fullDirFile).IsIgnored() {
+			hasIgnored = true
+		} else if cf, ok := f.model.CurrentFolderFile(f.ID, fullDirFile); !ok || cf.IsDeleted() || cf.IsInvalid() {
+			// Something appeared in the dir that we either are not
+			// aware of at all, that we think should be deleted or that
+			// is invalid, but not currently ignored -> schedule scan
+			scanChan <- fullDirFile
+			hasToBeScanned = true
+		} else {
+			// Dir contains file that is valid according to db and
+			// not ignored -> something weird is going on
+			hasKnown = true
+		}
+	}
+
+	if hasToBeScanned {
+		return errDirHasToBeScanned
+	}
+	if hasIgnored {
+		return errDirHasIgnored
+	}
+	if hasKnown {
+		return errDirNotEmpty
+	}
+
+	for _, del := range toBeDeleted {
+		f.fs.RemoveAll(del)
+	}
+
+	err := osutil.InWritableDir(f.fs.Remove, f.fs, dir)
+	if err == nil || fs.IsNotExist(err) {
+		// It was removed or it doesn't exist to start with
+		return nil
+	}
+	if _, serr := f.fs.Lstat(dir); serr != nil && !fs.IsPermission(serr) {
+		// We get an error just looking at the directory, and it's not a
+		// permission problem. Lets assume the error is in fact some variant
+		// of "file does not exist" (possibly expressed as some parent being a
+		// file and not a directory etc) and that the delete is handled.
+		return nil
+	}
+
+	return err
+}
+
 // A []fileError is sent as part of an event and will be JSON serialized.
 type fileError struct {
 	Path string `json:"path"`

lib/model/rwfolder_test.go

@@ -7,9 +7,11 @@
 package model
 
 import (
+	"bytes"
 	"context"
 	"crypto/rand"
 	"io"
+	"io/ioutil"
 	"os"
 	"path/filepath"
 	"testing"
@@ -17,6 +19,7 @@ import (
 
 	"github.com/syncthing/syncthing/lib/db"
 	"github.com/syncthing/syncthing/lib/fs"
+	"github.com/syncthing/syncthing/lib/ignore"
 	"github.com/syncthing/syncthing/lib/protocol"
 	"github.com/syncthing/syncthing/lib/scanner"
 	"github.com/syncthing/syncthing/lib/sync"
@@ -116,8 +119,9 @@ func TestHandleFile(t *testing.T) {
 	m := setUpModel(existingFile)
 	f := setUpSendReceiveFolder(m)
 	copyChan := make(chan copyBlocksState, 1)
+	dbUpdateChan := make(chan dbUpdateJob, 1)
 
-	f.handleFile(requiredFile, copyChan, nil)
+	f.handleFile(requiredFile, copyChan, nil, dbUpdateChan)
 
 	// Receive the results
 	toCopy := <-copyChan
@@ -157,8 +161,9 @@ func TestHandleFileWithTemp(t *testing.T) {
 	m := setUpModel(existingFile)
 	f := setUpSendReceiveFolder(m)
 	copyChan := make(chan copyBlocksState, 1)
+	dbUpdateChan := make(chan dbUpdateJob, 1)
 
-	f.handleFile(requiredFile, copyChan, nil)
+	f.handleFile(requiredFile, copyChan, nil, dbUpdateChan)
 
 	// Receive the results
 	toCopy := <-copyChan
@@ -207,11 +212,12 @@ func TestCopierFinder(t *testing.T) {
 	copyChan := make(chan copyBlocksState)
 	pullChan := make(chan pullBlockState, 4)
 	finisherChan := make(chan *sharedPullerState, 1)
+	dbUpdateChan := make(chan dbUpdateJob, 1)
 
 	// Run a single fetcher routine
 	go f.copierRoutine(copyChan, pullChan, finisherChan)
 
-	f.handleFile(requiredFile, copyChan, finisherChan)
+	f.handleFile(requiredFile, copyChan, finisherChan, dbUpdateChan)
 
 	pulls := []pullBlockState{<-pullChan, <-pullChan, <-pullChan, <-pullChan}
 	finish := <-finisherChan
@@ -331,13 +337,14 @@ func TestWeakHash(t *testing.T) {
 	copyChan := make(chan copyBlocksState)
 	pullChan := make(chan pullBlockState, expectBlocks)
 	finisherChan := make(chan *sharedPullerState, 1)
+	dbUpdateChan := make(chan dbUpdateJob, 1)
 
 	// Run a single fetcher routine
 	go fo.copierRoutine(copyChan, pullChan, finisherChan)
 
 	// Test 1 - no weak hashing, file gets fully repulled (`expectBlocks` pulls).
 	fo.WeakHashThresholdPct = 101
-	fo.handleFile(desiredFile, copyChan, finisherChan)
+	fo.handleFile(desiredFile, copyChan, finisherChan, dbUpdateChan)
 
 	var pulls []pullBlockState
 	for len(pulls) < expectBlocks {
@@ -365,7 +372,7 @@ func TestWeakHash(t *testing.T) {
 
 	// Test 2 - using weak hash, expectPulls blocks pulled.
 	fo.WeakHashThresholdPct = -1
-	fo.handleFile(desiredFile, copyChan, finisherChan)
+	fo.handleFile(desiredFile, copyChan, finisherChan, dbUpdateChan)
 
 	pulls = pulls[:0]
 	for len(pulls) < expectPulls {
@@ -444,11 +451,12 @@ func TestLastResortPulling(t *testing.T) {
 	copyChan := make(chan copyBlocksState)
 	pullChan := make(chan pullBlockState, 1)
 	finisherChan := make(chan *sharedPullerState, 1)
+	dbUpdateChan := make(chan dbUpdateJob, 1)
 
 	// Run a single copier routine
 	go f.copierRoutine(copyChan, pullChan, finisherChan)
 
-	f.handleFile(file, copyChan, finisherChan)
+	f.handleFile(file, copyChan, finisherChan, dbUpdateChan)
 
 	// Copier should hash empty file, realise that the region it has read
 	// doesn't match the hash which was advertised by the block map, fix it
@@ -491,11 +499,12 @@ func TestDeregisterOnFailInCopy(t *testing.T) {
 	pullChan := make(chan pullBlockState)
 	finisherBufferChan := make(chan *sharedPullerState)
 	finisherChan := make(chan *sharedPullerState)
+	dbUpdateChan := make(chan dbUpdateJob, 1)
 
 	go f.copierRoutine(copyChan, pullChan, finisherBufferChan)
-	go f.finisherRoutine(finisherChan)
+	go f.finisherRoutine(ignore.New(defaultFs), finisherChan, dbUpdateChan, make(chan string))
 
-	f.handleFile(file, copyChan, finisherChan)
+	f.handleFile(file, copyChan, finisherChan, dbUpdateChan)
 
 	// Receive a block at puller, to indicate that at least a single copier
 	// loop has been performed.
@@ -564,12 +573,13 @@ func TestDeregisterOnFailInPull(t *testing.T) {
 	pullChan := make(chan pullBlockState)
 	finisherBufferChan := make(chan *sharedPullerState)
 	finisherChan := make(chan *sharedPullerState)
+	dbUpdateChan := make(chan dbUpdateJob, 1)
 
 	go f.copierRoutine(copyChan, pullChan, finisherBufferChan)
 	go f.pullerRoutine(pullChan, finisherBufferChan)
-	go f.finisherRoutine(finisherChan)
+	go f.finisherRoutine(ignore.New(defaultFs), finisherChan, dbUpdateChan, make(chan string))
 
-	f.handleFile(file, copyChan, finisherChan)
+	f.handleFile(file, copyChan, finisherChan, dbUpdateChan)
 
 	// Receive at finisher, we should error out as puller has nowhere to pull
 	// from.
@@ -607,3 +617,37 @@ func TestDeregisterOnFailInPull(t *testing.T) {
 		t.Fatal("Didn't get anything to the finisher")
 	}
 }
+
+func TestIssue3164(t *testing.T) {
+	m := setUpModel(protocol.FileInfo{})
+	f := setUpSendReceiveFolder(m)
+
+	defaultFs.RemoveAll("issue3164")
+	defer defaultFs.RemoveAll("issue3164")
+
+	if err := defaultFs.MkdirAll("issue3164/oktodelete/foobar", 0777); err != nil {
+		t.Fatal(err)
+	}
+	if err := ioutil.WriteFile("testdata/issue3164/oktodelete/foobar/file", []byte("Hello"), 0644); err != nil {
+		t.Fatal(err)
+	}
+	if err := ioutil.WriteFile("testdata/issue3164/oktodelete/file", []byte("Hello"), 0644); err != nil {
+		t.Fatal(err)
+	}
+	file := protocol.FileInfo{
+		Name: "issue3164",
+	}
+
+	matcher := ignore.New(defaultFs)
+	if err := matcher.Parse(bytes.NewBufferString("(?d)oktodelete"), ""); err != nil {
+		t.Fatal(err)
+	}
+
+	dbUpdateChan := make(chan dbUpdateJob, 1)
+
+	f.handleDeleteDir(file, matcher, dbUpdateChan, make(chan string))
+
+	if _, err := defaultFs.Stat("testdata/issue3164"); !fs.IsNotExist(err) {
+		t.Fatal(err)
+	}
+}

lib/model/sharedpullerstate.go

@@ -96,24 +96,8 @@ func (s *sharedPullerState) tempFile() (io.WriterAt, error) {
 	// here.
 	dir := filepath.Dir(s.tempName)
 	if info, err := s.fs.Stat(dir); err != nil {
-		if fs.IsNotExist(err) {
+		s.failLocked("dst stat dir", err)
-			// XXX: This works around a bug elsewhere, a race condition when
+		return nil, err
-			// things are deleted while being synced. However that happens, we
-			// end up with a directory for "foo" with the delete bit, but a
-			// file "foo/bar" that we want to sync. We never create the
-			// directory, and hence fail to create the file and end up looping
-			// forever on it. This breaks that by creating the directory; on
-			// next scan it'll be found and the delete bit on it is removed.
-			// The user can then clean up as they like...
-			l.Infoln("Resurrecting directory", dir)
-			if err := s.fs.MkdirAll(dir, 0755); err != nil {
-				s.failLocked("resurrect dir", err)
-				return nil, err
-			}
-		} else {
-			s.failLocked("dst stat dir", err)
-			return nil, err
-		}
 	} else if info.Mode()&0200 == 0 {
 		err := s.fs.Chmod(dir, 0755)
 		if !s.ignorePerms && err == nil {