From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A3E6EC4338F for ; Tue, 27 Jul 2021 13:38:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8AB4A61A7F for ; Tue, 27 Jul 2021 13:38:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236644AbhG0Ni2 (ORCPT ); Tue, 27 Jul 2021 09:38:28 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36302 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236509AbhG0NiY (ORCPT ); Tue, 27 Jul 2021 09:38:24 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B7B04C061757; Tue, 27 Jul 2021 06:38:24 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:To:From:Date:Sender:Reply-To:Cc: Content-Transfer-Encoding:Content-ID:Content-Description; bh=EpSbFrEHGAQA1xr1naEuF16MkP61b5G7e9AV8x/Ex4E=; b=o3L8a9jEH3Ul9rQPCR8ay1CcPx wIvSa1TgAQ50cmZBTGLgdFt+6KKz9MeISZt2oLyJAD+VrxC8sVZkQDWVTFzAm7Iwxmpok/1Mp4p6l P3Nl2s2YEtHdeeEepN52ujuAy8ErrEuQsmZ0DzDilBtZpMXt8pbSZ387BLsESn7wQtqgtyy131Fgr V9tKJps9bOSaCDF4lQ4fPtAksGfWW7/qHx9sl878omOclcnrAte+06XMAscDe8xg0q4Zv3OxvS6QB 8i4Bw2KjwG4FkaEEwKm3MCpXkLEBkiiptKY01o0p92Uxi/IvCJJVRpyiIPCzrVvjXAgtyPhGczHr3 KaXHSOCg==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1m8NFL-00F2s7-Bz; Tue, 27 Jul 2021 13:36:29 +0000 Date: Tue, 27 Jul 2021 14:35:46 +0100 From: Matthew Wilcox To: dsterba@suse.cz, Christoph Hellwig , Andreas Gruenbacher , Gao Xiang , "Darrick J . Wong" , Huang Jianan , linux-erofs@lists.ozlabs.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Andreas Gruenbacher Subject: Re: [PATCH v7] iomap: make inline data support more flexible Message-ID: References: <20210723174131.180813-1-hsiangkao@linux.alibaba.com> <20210725221639.426565-1-agruenba@redhat.com> <20210726110611.459173-1-agruenba@redhat.com> <20210726121702.GA528@lst.de> <20210727082042.GI5047@twin.jikos.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210727082042.GI5047@twin.jikos.cz> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jul 27, 2021 at 10:20:42AM +0200, David Sterba wrote: > On Mon, Jul 26, 2021 at 02:17:02PM +0200, Christoph Hellwig wrote: > > > Subject: iomap: Support tail packing > > > > I can't say I like this "tail packing" language here when we have the > > perfectly fine inline wording. Same for various comments in the actual > > code. > > Yes please, don't call it tail-packing when it's an inline extent, we'll > use that for btrfs eventually and conflating the two terms has been > cofusing users. Except reiserfs, no linux filesystem does tail-packing. Hmm ... I see what reiserfs does as packing tails of multiple files into one block. What gfs2 (and ext4) do is inline data. Erofs packs the tail of a single file into the same block as the inode. If I understand what btrfs does correctly, it stores data in the btree. But (like gfs2/ext4), it's only for the entire-file-is-small case, not for its-just-ten-bytes-into-the-last-block case. So what would you call what erofs is doing if not tail-packing? Wikipedia calls it https://en.wikipedia.org/wiki/Block_suballocation which doesn't quite fit. We need a phrase which means "this isn't just for small files but for small tails of large files".