do_last(): fetch directory ->i_mode and ->i_uid before it's too late

may_create_in_sticky() call is done when we already have dropped the
reference to dir.

Fixes: 30aba6656f61e (namei: allow restricted O_CREAT of FIFOs and regular files)
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Change-Id: I395c97ab9d7aedbe3262e30068f22a0a3e11922f
Git-repo: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


Git-commit: d0cb50185ae942b03c4327be322055d622dc79f6
Signed-off-by: Alam Md Danish <amddan@codeaurora.org>