UPSTREAM: ext4/fscrypto: avoid RCU lookup in d_revalidate

commit 03a8bb0e53d9562276045bdfcf2b5de2e4cff5a1 upstream.

As Al pointed, d_revalidate should return RCU lookup before using d_inode.
This was originally introduced by:
commit 34286d66 ("fs: rcu-walk aware d_revalidate method").

Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit 16fb859f9b2bb246a18b4d0edc605774193c33b7)
Change-Id: Ib3e41f923f02845e0ef78d65706cdc0bde30b9d9
Signed-off-by: Eric Biggers <ebiggers@google.com>