From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx2.suse.de ([195.135.220.15]:52805 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752435AbcKNIyX (ORCPT ); Mon, 14 Nov 2016 03:54:23 -0500 Date: Mon, 14 Nov 2016 09:54:19 +0100 From: Jan Kara To: Ross Zwisler Cc: Jan Kara , Ted Tso , linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org, Christoph Hellwig Subject: Re: [PATCH 06/11] ext4: Avoid split extents for DAX writes Message-ID: <20161114085419.GC2524@quack2.suse.cz> References: <1478603297-11793-1-git-send-email-jack@suse.cz> <1478603297-11793-7-git-send-email-jack@suse.cz> <20161111202547.GA1569@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20161111202547.GA1569@linux.intel.com> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Fri 11-11-16 13:25:47, Ross Zwisler wrote: > On Tue, Nov 08, 2016 at 12:08:12PM +0100, Jan Kara wrote: > > Currently mapping of blocks for DAX writes happen with > > EXT4_GET_BLOCKS_PRE_IO flag set. That has a result that each > > ext4_map_blocks() call creates a separate written extent, although it > > could be merged to the neighboring extents in the extent tree. The > > reason for using this flag is that in case the extent is unwritten, we > > need to convert it to written one and zero it out. However this "convert > > mapped range to written" operation is already implemented by > > ext4_map_blocks() for the case of data writes into unwritten extent. So > > just use flags for that mode of operation, simplify the code, and avoid > > unnecessary split extents. > > > > Signed-off-by: Jan Kara > > The code that this patch modifies was just introduced in the previous patch. > Is there a reason to keep both patches, or would it be cleaner just to squash > them and have one patch that introduces the code as you intend for it to end > up? Well, the previous patch just mostly moved the block allocation logic from dedicated DAX get_block function into iomap_begin(). This patch changes the block allocation logic so I prefer to keep them separate - mostly for the sake of documenting the change how allocation of blocks for DAX works in the changelog. Honza -- Jan Kara SUSE Labs, CR