TAKE - tweak allocation size

[Steve Lord <lord@xxxxxxx>]

This brings the default amount of data xfs allocates back in line
with the code prior to the multiple blocksize work. Worth a few
percent on write speed.

Date:  Tue Jun  4 05:53:41 PDT 2002
Workarea:  jen.americas.sgi.com:/src/lord/xfs-baseline

The following file(s) were checked into:
  bonnie.engr.sgi.com:/isms/slinx/2.4.x-xfs


Modid:  2.4.x-xfs:slinx:120735a
linux/fs/xfs/xfs_mount.h - 1.143
        - Define XFS_WRITE_IO_LOG

linux/fs/xfs/linux/xfs_iops.c - 1.146
        - Use XFS_WRITE_IO_LOG as the size for extending allocations