From mboxrd@z Thu Jan 1 00:00:00 1970 From: Artem Bityutskiy Subject: [PATCHv3 09/14] writeback: restructure bdi forker loop a little Date: Thu, 22 Jul 2010 16:56:23 +0300 Message-ID: <1279806988-14100-10-git-send-email-dedekind1@gmail.com> References: <1279806988-14100-1-git-send-email-dedekind1@gmail.com> Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org To: Jens Axboe Return-path: Received: from smtp.nokia.com ([192.100.105.134]:52145 "EHLO mgw-mx09.nokia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932298Ab0GVN5H (ORCPT ); Thu, 22 Jul 2010 09:57:07 -0400 In-Reply-To: <1279806988-14100-1-git-send-email-dedekind1@gmail.com> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: From: Artem Bityutskiy This patch re-structures the loop which walks bdi a little. This is just a micro-step towards the coming change where the forker thread will kill the bdi threads. It should simplify reviewing the following changes, which would otherwise be larger. This patch also adds the 'bdi_cap_flush_forker(bdi)' condition check to the loop. The reason for this is that the forker thread can start _before_ the 'BDI_registered' flag is set (see 'bdi_register()'), so the WARN() statement will fire for the default bdi. I observed this warning at boot-up. This patch also amends comments a little. Signed-off-by: Artem Bityutskiy Reviewed-by: Christoph Hellwig --- mm/backing-dev.c | 28 +++++++++++++++++----------- 1 files changed, 17 insertions(+), 11 deletions(-) diff --git a/mm/backing-dev.c b/mm/backing-dev.c index 672c17b..b788b8e 100644 --- a/mm/backing-dev.c +++ b/mm/backing-dev.c @@ -348,25 +348,31 @@ static int bdi_forker_thread(void *ptr) * a thread registered. If so, set that up. */ list_for_each_entry(bdi, &bdi_list, bdi_list) { - if (!bdi_cap_writeback_dirty(bdi)) - continue; - if (bdi->wb.task) - continue; - if (list_empty(&bdi->work_list) && - !bdi_has_dirty_io(bdi)) + bool have_dirty_io; + + if (!bdi_cap_writeback_dirty(bdi) || + bdi_cap_flush_forker(bdi)) continue; WARN(!test_bit(BDI_registered, &bdi->state), "bdi %p/%s is not registered!\n", bdi, bdi->name); - fork = true; + have_dirty_io = !list_empty(&bdi->work_list) || + wb_has_dirty_io(&bdi->wb); /* - * Set the pending bit - if someone will try to - * unregister this bdi - it'll wait on this bit. + * If the bdi has work to do, but the thread does not + * exist - create it. */ - set_bit(BDI_pending, &bdi->state); - break; + if (!bdi->wb.task && have_dirty_io) { + /* + * Set the pending bit - if someone will try to + * unregister this bdi - it'll wait on this bit. + */ + set_bit(BDI_pending, &bdi->state); + fork = true; + break; + } } spin_unlock_bh(&bdi_lock); -- 1.7.1.1