From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751955AbZIYAtA (ORCPT ); Thu, 24 Sep 2009 20:49:00 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751202AbZIYAs7 (ORCPT ); Thu, 24 Sep 2009 20:48:59 -0400 Received: from mga03.intel.com ([143.182.124.21]:58571 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751092AbZIYAs7 (ORCPT ); Thu, 24 Sep 2009 20:48:59 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.44,448,1249282800"; d="scan'208";a="191451830" Date: Fri, 25 Sep 2009 08:48:55 +0800 From: Wu Fengguang To: Jens Axboe Cc: "linux-kernel@vger.kernel.org" , "Li, Shaohua" , "chris.mason@oracle.com" , "jack@suse.cz" Subject: Re: [PATCH 01/10] fs: Fix busyloop in wb_writeback() Message-ID: <20090925004855.GB6190@localhost> References: <1253803236-20760-1-git-send-email-jens.axboe@oracle.com> <1253803236-20760-2-git-send-email-jens.axboe@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1253803236-20760-2-git-send-email-jens.axboe@oracle.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Sep 24, 2009 at 10:40:27PM +0800, Jens Axboe wrote: > From: Jan Kara > > If all inodes are under writeback (e.g. in case when there's only one inode > with dirty pages), wb_writeback() with WB_SYNC_NONE work basically degrades > to busylooping until I_SYNC flags of the inode is cleared. Fix the problem by > waiting on I_SYNC flags of an inode on b_more_io list in case we failed to > write anything. > > CC: Wu Fengguang Tested-by: Wu Fengguang > Signed-off-by: Jan Kara > Signed-off-by: Jens Axboe > --- > fs/fs-writeback.c | 19 ++++++++++++++++++- > 1 files changed, 18 insertions(+), 1 deletions(-) > > diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c > index 8e1e5e1..c59d673 100644 > --- a/fs/fs-writeback.c > +++ b/fs/fs-writeback.c > @@ -706,6 +706,7 @@ static long wb_writeback(struct bdi_writeback *wb, > }; > unsigned long oldest_jif; > long wrote = 0; > + struct inode *inode; > > if (wbc.for_kupdate) { > wbc.older_than_this = &oldest_jif; > @@ -747,8 +748,24 @@ static long wb_writeback(struct bdi_writeback *wb, > * If we ran out of stuff to write, bail unless more_io got set > */ > if (wbc.nr_to_write > 0 || wbc.pages_skipped > 0) { > - if (wbc.more_io && !wbc.for_kupdate) > + if (wbc.more_io && !wbc.for_kupdate) { > + if (wbc.nr_to_write < MAX_WRITEBACK_PAGES) > + continue; > + /* > + * Nothing written. Wait for some inode to > + * become available for writeback. Otherwise > + * we'll just busyloop. > + */ > + spin_lock(&inode_lock); > + if (!list_empty(&wb->b_more_io)) { > + inode = list_entry( > + wb->b_more_io.prev, > + struct inode, i_list); > + inode_wait_for_writeback(inode); > + } > + spin_unlock(&inode_lock); > continue; > + } > break; > } > } > -- > 1.6.4.1.207.g68ea