vfs: do the careful dentry name access for all dentry_cmp cases
vfs: do the careful dentry name access for all dentry_cmp cases

Commit 12f8ad4b0533 ("vfs: clean up __d_lookup_rcu() and dentry_cmp()
interfaces") did the careful ACCESS_ONCE() of the dentry name only for
the word-at-a-time case, even though the issue is generic.

Admittedly I don't really see gcc ever reloading the value in the middle
of the loop, so the ACCESS_ONCE() protects us from a fairly theoretical
issue. But better safe than sorry.

Also, this consolidates the common parts of the word-at-a-time and
bytewise logic, which includes checking the length.  We'll be changing
that later.

Signed-off-by: Linus Torvalds <69652caca27c8b940640ad396ab71f93cacec34f@linux-foundation.org>

KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs