Branch b1_4

Branch b1_4
Description: 2.6 OST async journal commit and locking fix to improve performance
Details    : The filter_direct_io()+filter_commitrw_write() journal commits for
             2.6 kernels are now async as they already were in 2.4 kernels so
             that they can commit concurrently with the network bulk transfer.
             For block-allocated files the filter allocation semaphore is held
             to avoid filesystem fragmentation during allocation.  BKL lock
	     removed for 2.6 xattr operations where it is no longer needed.
b=7116
r=alex, tested at HP