From: Theodore Tso Subject: Re: [PATCH 1/2 V2] Direct IO for holes and fallocate: add end_io callback Date: Mon, 24 Aug 2009 15:11:38 -0400 Message-ID: <20090824191137.GA19624@mit.edu> References: <1250092470.18329.27.camel@mingming-laptop> <20090819141557.GA4705@atrey.karlin.mff.cuni.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Mingming , linux-ext4@vger.kernel.org, Eric Sandeen To: Jan Kara Return-path: Received: from thunk.org ([69.25.196.29]:58044 "EHLO thunker.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753204AbZHXTLn (ORCPT ); Mon, 24 Aug 2009 15:11:43 -0400 Content-Disposition: inline In-Reply-To: <20090819141557.GA4705@atrey.karlin.mff.cuni.cz> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Wed, Aug 19, 2009 at 04:15:57PM +0200, Jan Kara wrote: > > +static void ext4_end_io_dio(struct kiocb *iocb, loff_t offset, > > + ssize_t size, void *private) > > +{ > > + ext4_io_end_t *io_end = iocb->private; > > + struct workqueue_struct *wq; > > + > > + /* if not hole or unwritten extents, just simple return */ > > + if (!io_end || !size) > > + return; > > + io_end->offset = offset; > > + io_end->size = size; > > + wq = EXT4_SB(io_end->inode->i_sb)->dio_unwritten_wq; > > + > > + /* We need to convert unwritten extents to written */ > > + queue_work(wq, &io_end->work); > > + > > + if (is_sync_kiocb(iocb)) > > + flush_workqueue(wq); > I don't think you can flush_workqueue here. end_io is called from > interrupt context and flush_workqueue blocks for a long time... > The wait should be done in ext4_direct_IO IMHO... I don't see a problem here? This is a direct_io end_io callback, not a bio callback; so it's only called from an interrupt context in the async I/O case, and we only call flush_workqueue() when the kiocb is synchronous. - Ted