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/hfsplus_fs.h b/fs/hfsplus/hfsplus_fs.h
index 0d8532d..6255495 100644
--- a/fs/hfsplus/hfsplus_fs.h
+++ b/fs/hfsplus/hfsplus_fs.h
@@ -352,6 +352,7 @@
 int hfsplus_cat_write_inode(struct inode *);
 struct inode *hfsplus_new_inode(struct super_block *, int);
 void hfsplus_delete_inode(struct inode *);
+int hfsplus_file_fsync(struct file *file, int datasync);
 
 /* ioctl.c */
 long hfsplus_ioctl(struct file *filp, unsigned int cmd, unsigned long arg);