New IO engine implementation lost consuming grants by direct I/O
writes. That led to early emergence of out of space condition during
direct I/O. The below illustrates the problem:
  # OSTSIZE=100000 sh llmount.sh
  # dd if=/dev/zero of=/mnt/lustre/file bs=4k count=100 oflag=direct
  dd: error writing ‘/mnt/lustre/file’: No space left on device

Consume grants for direct I/O.

Try to consume grants in osc_queue_sync_pages() when it is called for
pages which are being writted in direct i/o.

Tests are added to verify grant consumption in buffered and direct i/o
and to verify direct i/o overwrite when ost is full.
The overwrite test is for ldiskfs only as zfs is unable to overwrite
when it is full.

Lustre-change: https://review.whamcloud.com/35896
Lustre-commit: 05f326a7

Fixes: 9fe4b52a

 ("LU-1030 osc: new IO engine implementation")
Signed-off-by: Vladimir Saveliev <c17830@cray.com>
Change-Id: I9a199452c564e8e8ad02f79231e8481...