LU-12681 osc: wrong cache of LVB attrs

LU-12681 osc: wrong cache of LVB attrs

osc object keeps the cache of LVB, obtained on lock enqueue, in
lov_oinfo. This cache gets all the modifications happenning on
the client, whereas the original LVB in locks does not get them.
At the same time, this cache is lost on object destroy, which
may appear on layout change in particular.

ldlm locks are left in LRU and could be matched on next operations.
First enqueue does not match a lock in LRU due to @kms_ignore in
enqueue_base, however if the lock will be obtained on a small offset
with some locks existent in LRU on larger offsets, the obtained size
will be cut by the policy region when set to KMS.

2nd enqueue can already match and add stale data to oinfo. Thus the
OSC cache is left with a small KMS. However the logic of preparing
a partial page code checks the KMS to decide if to read a page and
as it is small,the page is not read and therefore the non-read part
of the page is zeroed.

The object destroy detaches dlm locks from osc object, offload the
current osc oinfo cache to all the locks, so that it could be
reconstructed for the next osc oinfo. Introduce per-lock flag to
control the cached attribute status and drop re-enqueue after osc
object replacement.

This patch also fixes the handling of KMS_IGNORE added in LU-11964. It
is used only for skip the self lock in a search there is no other logic
for it and it is not needed for DOM locks at all - all the relevant
semantics is supposed to be accomplished by cbpending flag.

Signed-off-by: Vitaly Fertman <c17818@cray.com>
Cray-bug-id: LUS-7731
Change-Id: Iba45bb3e5ee181c82c2f22deb299228b1519cddb
Reviewed-on: https://review.whamcloud.com/36199
Tested-by: jenkins <devops@whamcloud.com>
Reviewed-by: Patrick Farrell <pfarrell@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Mike Pershin <mpershin@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>