commit babef37d upstream.

As it is, short copy in write() to append-only file will fail
to truncate the excessive allocated blocks.  As the matter of
fact, all checks in ufs_truncate_blocks() are either redundant
or wrong for that caller.  As for the only other caller
(ufs_evict_inode()), we only need the file type checks there.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
[bwh: Backported to 3.2:
 - No functions need to be renamed
 - Adjust filenames, context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>