hfsplus: write up fsync for directories

fsync is supposed to not just work on regular files, but also on
directories.  Fortunately enough hfsplus_file_fsync works just fine
for directories, so we can just wire it up.

Signed-off-by: Christoph Hellwig <hch@tuxera.com>
diff --git a/fs/hfsplus/inode.c b/fs/hfsplus/inode.c
index be68961..8cd8dc2 100644
--- a/fs/hfsplus/inode.c
+++ b/fs/hfsplus/inode.c
@@ -302,7 +302,7 @@
 	return 0;
 }
 
-static int hfsplus_file_fsync(struct file *file, int datasync)
+int hfsplus_file_fsync(struct file *file, int datasync)
 {
 	struct inode *inode = file->f_mapping->host;
 	struct hfsplus_sb_info *sbi = HFSPLUS_SB(inode->i_sb);