Relaxed inUse definition

src/main/java/org/cryptomator/frontend/fuse/OpenFile.java

@@ -19,11 +19,15 @@ public class OpenFile implements Closeable {
  private final Path path;
  private final FileChannel channel;
 
+ //"volatile" is fine, since methods of OpenFile ar externally synchronized
+ private volatile boolean dirty;
+
  private OpenFile(Path path, FileChannel channel) {
  this.path = path;
  this.channel = channel;
+ this.dirty = false;
  }
- 
+
  static OpenFile create(Path path, Set<? extends OpenOption> options, FileAttribute<?>... attrs) throws IOException {
  FileChannel ch = FileChannel.open(path, options, attrs);
  return new OpenFile(path, ch);
@@ -69,6 +73,7 @@ public int read(ByteBuffer buf, long num, long offset) throws IOException {
  * @throws IOException If an exception occurs during write.
  */
  public int write(ByteBuffer buf, long num, long offset) throws IOException {
+ dirty = true;
  if (num > Integer.MAX_VALUE) {
  throw new IOException("Requested too many bytes");
  }
@@ -80,13 +85,23 @@ public int write(ByteBuffer buf, long num, long offset) throws IOException {
  return written;
  }
 
+ /**
+ * Tests, if the write method of this open file was called at least once.
+ *
+ * @return {@code true} if {@link OpenFile#write(ByteBuffer, long, long)} was called on this object, otherwise {@code false}
+ */
+ boolean isDirty() {
+ return dirty;
+ }
+
  @Override
  public void close() throws IOException {
  channel.close();
  }
 
  public void fsync(boolean metaData) throws IOException {
  channel.force(metaData);
+ dirty = false;
  }
 
  public void truncate(long size) throws IOException {

src/main/java/org/cryptomator/frontend/fuse/OpenFileFactory.java

@@ -67,8 +67,15 @@ public void close(long fileHandle) throws ClosedChannelException, IOException {
  }
  }
 
- public int getOpenFileCount(){
- return openFiles.size();
+ /**
+ * Tests, if there exists dirty {@link OpenFile}s
+ * This method is neither atomic regarding the set of open files nor regarding each open file individually. Therefore, external synchronization is required.
+ *
+ * @return {@code true} if and only if at least one dirty {@link OpenFile} exists. Otherwise {@code false}.
+ * @see OpenFile#isDirty()
+ */
+ boolean hastDirtyOpenFiles() {
+ return openFiles.entrySet().stream().anyMatch(entry -> entry.getValue().isDirty());
  }
 
  /**

src/main/java/org/cryptomator/frontend/fuse/ReadOnlyAdapter.java

@@ -32,7 +32,6 @@
 import java.util.Collections;
 import java.util.EnumSet;
 import java.util.Set;
-import java.util.function.BooleanSupplier;
 
 public sealed class ReadOnlyAdapter implements FuseNioAdapter permits ReadWriteAdapter {
 
@@ -48,7 +47,6 @@ public sealed class ReadOnlyAdapter implements FuseNioAdapter permits ReadWriteA
  private final ReadOnlyDirectoryHandler dirHandler;
  private final ReadOnlyFileHandler fileHandler;
  private final ReadOnlyLinkHandler linkHandler;
- private final BooleanSupplier hasOpenFiles;
 
  protected ReadOnlyAdapter(Errno errno, Path root, int maxFileNameLength, FileNameTranscoder fileNameTranscoder, FileStore fileStore, OpenFileFactory openFiles, ReadOnlyDirectoryHandler dirHandler, ReadOnlyFileHandler fileHandler) {
  this.errno = errno;
@@ -61,7 +59,6 @@ protected ReadOnlyAdapter(Errno errno, Path root, int maxFileNameLength, FileNam
  this.dirHandler = dirHandler;
  this.fileHandler = fileHandler;
  this.linkHandler = new ReadOnlyLinkHandler(fileNameTranscoder);
- this.hasOpenFiles = () -> openFiles.getOpenFileCount() != 0;
  }
 
  public static ReadOnlyAdapter create(Errno errno, Path root, int maxFileNameLength, FileNameTranscoder fileNameTranscoder) {
@@ -305,7 +302,7 @@ public void destroy() {
  @Override
  public boolean isInUse() {
  try (PathLock pLock = lockManager.tryLockForWriting("/")) {
- return hasOpenFiles.getAsBoolean();
+ return openFiles.hastDirtyOpenFiles();
  } catch (AlreadyLockedException e) {
  return true;
  }
@@ -320,7 +317,7 @@ public void close() throws IOException {
  * Attempts to get a specific error code that best describes the given exception.
  * As a side effect this logs the error.
  *
- * @param e An exception
+ * @param e  An exception
  * @param opDesc A human-friendly string describing what operation was attempted (for logging purposes)
  * @return A specific error code or -EIO.
  */
@@ -331,8 +328,8 @@ protected int getErrorCodeForGenericFileSystemException(FileSystemException e, S
 // LOG.warn("{} {} failed, name too long.", opDesc);
 // return -ErrorCodes.ENAMETOOLONG();
 // } else {
-  LOG.error(opDesc + " failed.", e);
-  return -errno.eio();
+ LOG.error(opDesc + " failed.", e);
+ return -errno.eio();
 // }
  }
 }