From: Eric Sandeen Subject: Re: [PATCH] ext4: queue conversion after adding to inode's completed IO list Date: Thu, 07 Oct 2010 12:23:56 -0500 Message-ID: <4CAE022C.7050504@redhat.com> References: <4C5C67FD.5070208@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Jiaying Zhang To: ext4 development Return-path: Received: from mx1.redhat.com ([209.132.183.28]:43932 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750962Ab0JGRYB (ORCPT ); Thu, 7 Oct 2010 13:24:01 -0400 In-Reply-To: <4C5C67FD.5070208@redhat.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: On 08/06/2010 02:52 PM, Eric Sandeen wrote: > By queuing the io end on the unwritten workqueue before adding it > to our inode's list of completed IOs, I think we run the risk > of the work getting completed, and the IO freed, before we try > to add it to the inode's i_completed_io_list. > > It should be safe to add it to the inode's list of completed > IOs, and -then- queue it for completion, I think. Ping? would be good to fix this race, this has jiaying's ack too. > Thanks to Dave Chinner for pointing out the race. > > Signed-off-by: Eric Sandeen > --- > > (At least I think this is right; I haven't actually demonstrated a race...) > > diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c > index 0afc8c1..7f56c48 100644 > --- a/fs/ext4/inode.c > +++ b/fs/ext4/inode.c > @@ -3804,14 +3804,14 @@ static void ext4_end_io_dio(struct kiocb *iocb, loff_t offset, > io_end->flag = EXT4_IO_UNWRITTEN; > wq = EXT4_SB(io_end->inode->i_sb)->dio_unwritten_wq; > > - /* queue the work to convert unwritten extents to written */ > - queue_work(wq, &io_end->work); > - > /* Add the io_end to per-inode completed aio dio list*/ > ei = EXT4_I(io_end->inode); > spin_lock_irqsave(&ei->i_completed_io_lock, flags); > list_add_tail(&io_end->list, &ei->i_completed_io_list); > spin_unlock_irqrestore(&ei->i_completed_io_lock, flags); > + > + /* queue the work to convert unwritten extents to written */ > + queue_work(wq, &io_end->work); > iocb->private = NULL; > out: > if (is_async) > > -- > To unsubscribe from this list: send the line "unsubscribe linux-ext4" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html