xfs: split xfs_setattr

Split up xfs_setattr into two functions, one for the complex truncate
handling, and one for the trivial attribute updates.  Also move both
new routines to xfs_iops.c as they are fairly Linux-specific.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Alex Elder <aelder@sgi.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
diff --git a/fs/xfs/linux-2.6/xfs_file.c b/fs/xfs/linux-2.6/xfs_file.c
index 7f782af..8073f61 100644
--- a/fs/xfs/linux-2.6/xfs_file.c
+++ b/fs/xfs/linux-2.6/xfs_file.c
@@ -944,7 +944,7 @@
 
 		iattr.ia_valid = ATTR_SIZE;
 		iattr.ia_size = new_size;
-		error = -xfs_setattr(ip, &iattr, XFS_ATTR_NOLOCK);
+		error = -xfs_setattr_size(ip, &iattr, XFS_ATTR_NOLOCK);
 	}
 
 out_unlock: