md/raid1: restore ability for check and repair to fix read errors.

commit 30bc9b53878a9921b02e3b5bc4283ac1c6de102a
    md/raid1: fix bio handling problems in process_checks()

Move the bio_reset() to a point before where BIO_UPTODATE is checked,
so that check now always report that the bio is uptodate, even if it is not.

This causes process_check() to sometimes treat read-errors as
successful matches so the good data isn't written out.

This patch preserves the flag until it is needed.

Bug was introduced in 3.11, but backported to 3.10-stable (as it fixed
an even worse bug).  So suitable for any -stable since 3.10.

Reported-and-tested-by: Michael Tokarev <mjt@tls.msk.ru>
Cc: stable@vger.kernel.org (3.10+)
Fixed: 30bc9b53878a9921b02e3b5bc4283ac1c6de102a
Signed-off-by: NeilBrown <neilb@suse.de>
nfsd4: fix acl buffer overrun

4ac7249ea5a0ceef9f8269f63f33cc873c3fac61 "nfsd: use get_acl and
->set_acl" forgets to set the size in the case get_acl() succeeds, so
_posix_to_nfsv4_one() can then write past the end of its allocation.
Symptoms were slab corruption warnings.

Also, some minor cleanup while we're here.  (Among other things, note
that the first few lines guarantee that pacl is non-NULL.)

Signed-off-by: J. Bruce Fields <bfields@redhat.com>
md/raid5: Fix CPU hotplug callback registration

Subsystems that want to register CPU hotplug callbacks, as well as perform
initialization for the CPUs that are already online, often do it as shown
below:

	get_online_cpus();

	for_each_online_cpu(cpu)
		init_cpu(cpu);

	register_cpu_notifier(&foobar_cpu_notifier);

	put_online_cpus();

This is wrong, since it is prone to ABBA deadlocks involving the
cpu_add_remove_lock and the cpu_hotplug.lock (when running concurrently
with CPU hotplug operations).

Interestingly, the raid5 code can actually prevent double initialization and
hence can use the following simplified form of callback registration:

	register_cpu_notifier(&foobar_cpu_notifier);

	get_online_cpus();

	for_each_online_cpu(cpu)
		init_cpu(cpu);

	put_online_cpus();

A hotplug operation that occurs between registering the notifier and calling
get_online_cpus(), won't disrupt anything, because the code takes care to
perform the memory allocations only once.

So reorganize the code in raid5 this way to fix the deadlock with callback
registration.

Cc: linux-raid@vger.kernel.org
Cc: stable@vger.kernel.org (v2.6.32+)
Fixes: 36d1c6476be51101778882897b315bd928c8c7b5
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
[Srivatsa: Fixed the unregister_cpu_notifier() deadlock, added the
free_scratch_buffer() helper to condense code further and wrote the changelog.]
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: NeilBrown <neilb@suse.de>
lockd: send correct lock when granting a delayed lock.

If an NFS client attempts to get a lock (using NLM) and the lock is
not available, the server will remember the request and when the lock
becomes available it will send a GRANT request to the client to
provide the lock.

If the client already held an adjacent lock, the GRANT callback will
report the union of the existing and new locks, which can confuse the
client.

This happens because __posix_lock_file (called by vfs_lock_file)
updates the passed-in file_lock structure when adjacent or
over-lapping locks are found.

To avoid this problem we take a copy of the two fields that can
be changed (fl_start and fl_end) before the call and restore them
afterwards.
An alternate would be to allocate a 'struct file_lock', initialise it,
use locks_copy_lock() to take a copy, then locks_release_private()
after the vfs_lock_file() call.  But that is a lot more work.

Reported-by: Olaf Kirch <okir@suse.com>
Signed-off-by: NeilBrown <neilb@suse.de>
Cc: stable@vger.kernel.org
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

--
v1 had a couple of issues (large on-stack struct and didn't really work properly).
This version is much better tested.
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Merge tag 'md/3.14-fixes' of git://neil.brown.name/md

Pull md fixes from Neil Brown:
 "Two bugfixes for md

  both tagged for -stable"

* tag 'md/3.14-fixes' of git://neil.brown.name/md:
  md/raid5: Fix CPU hotplug callback registration
  md/raid1: restore ability for check and repair to fix read errors.
Merge branch 'for-3.14' of git://linux-nfs.org/~bfields/linux

Pull two nfsd bugfixes from Bruce Fields.

* 'for-3.14' of git://linux-nfs.org/~bfields/linux:
  lockd: send correct lock when granting a delayed lock.
  nfsd4: fix acl buffer overrun