LU-4505 quota: race of edquot updating

The slave edquot flag could be set mistakenly as following:

- slave A acquires quota from master, master found that the
  user is running out of quota, set edquot in reply;
- another slave deletes files and release quota to master,
  master clears edquot and notify all slaves by glimpse;
- glimpse reaches slave A before the reply of dqacq, so
  edquot flag will be set on slave A at the end.

Given that edquot can't be fully trusted, it should only be
used for enabling/disabling pre-aquire, but not for acquire.

Signed-off-by: Niu Yawei <yawei.niu@intel.com>
Change-Id: Id4db47462bdf620a42cd31f75726fbcaff869179
LU-4529 quota: call qsd_op_end() after trasn stop

qsd_op_end() shouldn't be called before the transaction stopped,
because qsd_op_end() is a quite heavy operation which could
probably allocate memory with standard allocator flag (__GFP_IO),
and allocating memory could result in dirty flush on other
filesystems, that will lead to opening transaction on different
journal and trigger the assert in jbd2_journal_start():
J_ASSERT(handle->h_transaction->t_journal == journal) at the end.

Signed-off-by: Niu Yawei <yawei.niu@intel.com>
Change-Id: I4ea3ff011fa7e44460b9912050e90b174813e01a