s390: fix machine check handling

Commit eb7e7d76 "s390: Replace __get_cpu_var uses" broke machine check
handling.

We copy machine check information from per-cpu to a stack variable for
local processing. Next we should zap the per-cpu variable, not the
stack variable.

Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
jbd2: fix regression where we fail to initialize checksum seed when loading

When we're enabling journal features, we cannot use the predicate
jbd2_journal_has_csum_v2or3() because we haven't yet set the sb
feature flag fields!  Moreover, we just finished loading the shash
driver, so the test is unnecessary; calculate the seed always.

Without this patch, we fail to initialize the checksum seed the first
time we turn on journal_checksum, which means that all journal blocks
written during that first mount are corrupt.  Transactions written
after the second mount will be fine, since the feature flag will be
set in the journal superblock.  xfstests generic/{034,321,322} are the
regression tests.

(This is important for 3.18.)

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.coM>
Reported-by: Eric Whitney <enwlinux@gmail.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Merge tag 'ext4_for_linus_urgent' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4

Pull ext4 bugfix from Ted Ts'o:
 "Fix an ext4 metadata checksum regression introduced in v3.18-rc3"

* tag 'ext4_for_linus_urgent' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4:
  jbd2: fix regression where we fail to initialize checksum seed when loading