Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753423Ab2BIIMd (ORCPT ); Thu, 9 Feb 2012 03:12:33 -0500 Received: from mga14.intel.com ([143.182.124.37]:40895 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756556Ab2BIIMa (ORCPT ); Thu, 9 Feb 2012 03:12:30 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.71,315,1320652800"; d="scan'208";a="104820187" Date: Thu, 9 Feb 2012 16:02:24 +0800 From: Wu Fengguang To: Dave Chinner Cc: Andrew Morton , linux-fsdevel@vger.kernel.org, LKML , Jens Axboe , Li Shaohua Subject: Re: [PATCH] block: remove plugging at buffered write time Message-ID: <20120209080224.GA28465@localhost> References: <20120208110143.GA5550@localhost> <20120208232719.GD7479@dastard> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120208232719.GD7479@dastard> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1523 Lines: 40 On Thu, Feb 09, 2012 at 10:27:19AM +1100, Dave Chinner wrote: > On Wed, Feb 08, 2012 at 07:01:44PM +0800, Wu Fengguang wrote: > > Buffered write(2) is not directly tied to IO, so it's not suitable to > > handle plug in generic_file_aio_write(). > > But generic_sync_write() does issue IO for O_SYNC writes, so unless > there is plugging at a lower layer in the writeback code then it > appears to me that plugging is still necessary (at least inside the > sync branch).... Good catch! It looks that generic_write_sync() eventually calls into vfs_fsync_range() which further calls ->fsync(). We may add plugging around it: --- linux-next.orig/fs/sync.c 2012-02-09 15:59:52.000000000 +0800 +++ linux-next/fs/sync.c 2012-02-09 16:01:02.000000000 +0800 @@ -164,9 +164,17 @@ SYSCALL_DEFINE1(syncfs, int, fd) */ int vfs_fsync_range(struct file *file, loff_t start, loff_t end, int datasync) { + struct blk_plug plug; + int ret; + if (!file->f_op || !file->f_op->fsync) return -EINVAL; - return file->f_op->fsync(file, start, end, datasync); + + blk_start_plug(&plug); + ret = file->f_op->fsync(file, start, end, datasync); + blk_finish_plug(&plug); + + return ret; } EXPORT_SYMBOL(vfs_fsync_range); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/