hfsplus: optimize fsync

Avoid doing unessecary work in fsync.  Do nothing unless the inode
was marked dirty, and only write the various metadata inodes out if
they contain any dirty state from this inode.  This is archived by
adding three new dirty bits to the hfsplus-specific inode which are
set in the correct places.

Signed-off-by: Christoph Hellwig <hch@tuxera.com>
diff --git a/fs/hfsplus/ioctl.c b/fs/hfsplus/ioctl.c
index 40a85a3..f5a7224 100644
--- a/fs/hfsplus/ioctl.c
+++ b/fs/hfsplus/ioctl.c
@@ -147,9 +147,11 @@
 			res = -ERANGE;
 	} else
 		res = -EOPNOTSUPP;
-	if (!res)
+	if (!res) {
 		hfs_bnode_write(fd.bnode, &entry, fd.entryoffset,
 				sizeof(struct hfsplus_cat_file));
+		hfsplus_mark_inode_dirty(inode, HFSPLUS_I_CAT_DIRTY);
+	}
 out:
 	hfs_find_exit(&fd);
 	return res;