TAKE 794398 - reservations not cleared on O_TRUNC

[lord@xxxxxxx]

This was broken because the open with O_TRUNC code path on linux goes into
the filesystem via a different route from on irix. 

Date:  Wed Jun 28 08:03:03 PDT 2000
Workarea:  jen.cray.com:/src/lord/xfs-linux.2.4.0-test1

The following file(s) were checked into:
  bonnie.engr.sgi.com:/isms/slinx/2.4.0-test1-xfs


Modid:  2.4.0-test1-xfs:slinx:65389a
linux/fs/xfs/xfs_vnodeops.c - 1.457
http://oss.sgi.com/cgi-bin/cvsweb.cgi/linux-2.4-xfs/linux/fs/xfs/xfs_vnodeops.c.diff?r1=text&tr1=1.457&r2=text&tr2=1.456&f=h
        - Modify setattr in the truncate to zero case to pay attention to
          existing extents beying end of file, open with O_TRUNC comes this way
          in Linux.