staging: lustre: lov: adjust page bufsize after layout change

staging: lustre: lov: adjust page bufsize after layout change

Otherwise, the coh_page_bufsize keeps increasing when the file's
layout keeps changing in lov_init_raid0().

Signed-off-by: Jinshan Xiong <jinshan.xiong@intel.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-5459
Reviewed-on: http://review.whamcloud.com/11394
Reviewed-by: frank zago <fzago@cray.com>
Reviewed-by: Bobi Jam <bobijam@gmail.com>
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: James Simmons <jsimmons@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>