fusefrontend: implement fsync on directories

Fixes https://github.com/rfjakob/gocryptfs/issues/587

2 files changed, 23 insertions, 1 deletions

diff --git a/internal/fusefrontend/file.go b/internal/fusefrontend/file.go
index cbf78e9..4866e65 100644
--- a/internal/fusefrontend/file.go
+++ b/internal/fusefrontend/file.go
@@ -427,7 +427,10 @@ func (f *File) Flush(ctx context.Context) syscall.Errno {
 	return fs.ToErrno(err)
 }
 
-// Fsync FUSE call
+// Fsync: handles FUSE opcode FSYNC
+//
+// Unfortunately, as Node.Fsync is also defined and takes precedence,
+// File.Fsync is never called at the moment.
 func (f *File) Fsync(ctx context.Context, flags uint32) (errno syscall.Errno) {
 	f.fdLock.RLock()
 	defer f.fdLock.RUnlock()
diff --git a/internal/fusefrontend/node.go b/internal/fusefrontend/node.go
index dd446a3..5d3c178 100644
--- a/internal/fusefrontend/node.go
+++ b/internal/fusefrontend/node.go
@@ -447,3 +447,22 @@ func (n *Node) Rename(ctx context.Context, name string, newParent fs.InodeEmbedd
 	}
 	return 0
 }
+
+// Fsync: handles FUSE opcodes FSYNC & FDIRSYNC
+//
+// Note: f is always set to nil by go-fuse
+func (n *Node) Fsync(ctx context.Context, f fs.FileHandle, flags uint32) syscall.Errno {
+	dirfd, cName, errno := n.prepareAtSyscallMyself()
+	if errno != 0 {
+		return errno
+	}
+	defer syscall.Close(dirfd)
+
+	fd, err := syscallcompat.Openat(dirfd, cName, syscall.O_RDONLY|syscall.O_NOFOLLOW, 0)
+	if err != nil {
+		return fs.ToErrno(err)
+	}
+	defer syscall.Close(fd)
+
+	return fs.ToErrno(syscall.Fsync(fd))
+}