commit 44b1d530 upstream.

Add d_is_dir(dentry) helper which is analogous to S_ISDIR().

To avoid confusion, rename d_is_directory() to d_can_lookup().
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Reviewed-by: J. Bruce Fields <bfields@redhat.com>
[ kamal: 3.13-stable prereq for a9c8259 "CIFS: Fix directory rename error" ]
Signed-off-by: Kamal Mostafa <kamal@canonical.com>