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=-19.2 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham 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 1DAD1C4338F for ; Tue, 17 Aug 2021 10:11:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E2C0D60F41 for ; Tue, 17 Aug 2021 10:11:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235556AbhHQKMS (ORCPT ); Tue, 17 Aug 2021 06:12:18 -0400 Received: from smtp-out1.suse.de ([195.135.220.28]:40210 "EHLO smtp-out1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235376AbhHQKMR (ORCPT ); Tue, 17 Aug 2021 06:12:17 -0400 Received: from imap1.suse-dmz.suse.de (imap1.suse-dmz.suse.de [192.168.254.73]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id 527BE21D61; Tue, 17 Aug 2021 10:11:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1629195104; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=SZ5TojIfeqMBzO0nHXS24zMY0/4UEL05GGUG4m8jSVA=; b=pjDkP1Y+d+zyV/aKri/K8akaRXBISPVnLyo4kD0K39Mw11unwGSXqsTSnNUml9QaZiReVZ WThI5lPfqwBt92OQGSQLEdItuo+w4GgcYar0gcBoYyAqLJdcr18zvEEzpTLE89T9CnmBDJ UBskjuHt1n5JYfsT65nzI60cz0uuuog= Received: from imap1.suse-dmz.suse.de (imap1.suse-dmz.suse.de [192.168.254.73]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap1.suse-dmz.suse.de (Postfix) with ESMTPS id 2B01E13318; Tue, 17 Aug 2021 10:11:44 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap1.suse-dmz.suse.de with ESMTPSA id fRjiB2CLG2ETEwAAGKfGzw (envelope-from ); Tue, 17 Aug 2021 10:11:44 +0000 Subject: Re: [PATCH v2 3/4] btrfs: introduce btrfs_subpage_bitmap_info To: Qu Wenruo , linux-btrfs@vger.kernel.org References: <20210817093852.48126-1-wqu@suse.com> <20210817093852.48126-4-wqu@suse.com> From: Nikolay Borisov Message-ID: <7b9c1c27-1938-4702-e6b2-db5a840f7a84@suse.com> Date: Tue, 17 Aug 2021 13:11:43 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: <20210817093852.48126-4-wqu@suse.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On 17.08.21 г. 12:38, Qu Wenruo wrote: > Currently we use fixed size u16 bitmap for subpage bitmap. > This is fine for 4K sectorsize with 64K page size. > > But for 4K sectorsize and larger page size, the bitmap is too small, > while for smaller page size like 16K, u16 bitmaps waste too much space. > > Here we introduce a new helper structure, btrfs_subpage_bitmap_info, to > record the proper bitmap size, and where each bitmap should start at. > > By this, we can later compact all subpage bitmaps into one u32 bitmap. > > This patch is the first step towards such compact bitmap. > > Signed-off-by: Qu Wenruo > --- > fs/btrfs/ctree.h | 1 + > fs/btrfs/disk-io.c | 12 +++++++++--- > fs/btrfs/subpage.c | 35 +++++++++++++++++++++++++++++++++++ > fs/btrfs/subpage.h | 36 ++++++++++++++++++++++++++++++++++++ > 4 files changed, 81 insertions(+), 3 deletions(-) > > +/* > + * Extra info for subpapge bitmap. > + * > + * For subpage we pack all uptodate/error/dirty/writeback/ordered > + * bitmaps into one larger bitmap. > + * > + * This structure records how they are organized in such bitmap: > + * > + * /- uptodate_offset /- error_offset /- dirty_offset > + * | | | > + * v v v > + * |u|u|u|u|........|u|u|e|e|.......|e|e| ... |o|o| nit: the 'e' that the dirty offset is pointing to should be a 'd', I'm sure David can fix this while merging.