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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A6BF3C77B73 for ; Sun, 4 Jun 2023 19:06:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229670AbjFDTGw (ORCPT ); Sun, 4 Jun 2023 15:06:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44838 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230437AbjFDTGv (ORCPT ); Sun, 4 Jun 2023 15:06:51 -0400 Received: from mail-oi1-x236.google.com (mail-oi1-x236.google.com [IPv6:2607:f8b0:4864:20::236]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 06192120 for ; Sun, 4 Jun 2023 12:06:45 -0700 (PDT) Received: by mail-oi1-x236.google.com with SMTP id 5614622812f47-39a55e5cfc0so3745296b6e.3 for ; Sun, 04 Jun 2023 12:06:45 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20221208; t=1685905605; x=1688497605; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=gxCtGKB4/odZJcA7XOpbwNyB264buEilxJGo+B0loX0=; b=Ni0UvMVjnsuWgPAoPrAmzZ1oRCkyCzt68KqPSDQHkxO9Mt860D9eMt2unWPzXkiJKj tDLqhpdHlslgIACupQh/hLeu7hkvKJeBOyoGjSUmGHnnvPN/CVZY7W1JcU6/NCOOlDb7 rxNFK6+5CffFG126EolBPYBeEunUL624+kJZ7aSPI5ulJHKF1bwu/Qi6MBUcGYBlPGDN rrHiJx/rCs/CdUF5iyUpoanrH3Rm7X4ffWvKFNqYmo337URQmegw8zEh4kQebWy8lydN z1XLKrQMMnoqLWE7tWE5GjmINLye2k5wVkJMQV8/38UhFHRTZJN4WHqmPbF2RN8RxVxZ Dc3Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1685905605; x=1688497605; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=gxCtGKB4/odZJcA7XOpbwNyB264buEilxJGo+B0loX0=; b=KBCK9KPnF8kdPz/IQUjvCSdY7Nm/PIaTGnLftY8y92PBttsMnXLF7/4MQqb1UzAQ7n Ldr+mHi0upmHxlvUpcvvANGf+ljAKZ9v7/NPhUFV4/uQOP+Mey8wY26vupVhXxwosWsN 4AbJqI2lVRLDiLVejDXTOZ3+r1y+I3MXBDGe7j9qMhXKUpqup6PawzbLjIHRF1RmjBze MCeGbcls0fuaEYZdZsVFJWAEo4coBNpnOmnqb9NlPL8OhgLYzaOJ4uxchggG3E8BnmOz 4zzZxsek1dI8kNxVkb64iTXoUJ+c6UhP2s6PzxmH8qHKbLlnvHkusiF0sqAF/ul4k2Q9 cyDA== X-Gm-Message-State: AC+VfDzwiS8gUusa1rRqJoJDcIZSZCiW/CMYiYBjZOkoqW3FjV6Ms855 +5bEJ3UXe9L2DRPNNrtf+lgSf6d74rwfSg== X-Google-Smtp-Source: ACHHUZ6ssUXm3UcAeNUYG9nhiMci3N0tZ8dME7Nxi/34YBG3u2FiT/w1W4ogjgwvVjSTmURMis1QwA== X-Received: by 2002:a05:6808:298f:b0:398:ad87:2dab with SMTP id ex15-20020a056808298f00b00398ad872dabmr5904321oib.5.1685905604851; Sun, 04 Jun 2023 12:06:44 -0700 (PDT) Received: from localhost.localdomain ([76.132.108.20]) by smtp.gmail.com with ESMTPSA id m8-20020a170902db0800b001a6ed2d0ef8sm4979072plx.273.2023.06.04.12.06.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 04 Jun 2023 12:06:44 -0700 (PDT) From: Russell Harmon To: bagasdotme@gmail.com Cc: mpatocka@redhat.com, snitzer@redhat.com, dm-devel@redhat.com, linux-doc@vger.kernel.org, Russell Harmon Subject: [PATCH v3 2/4] Documents the meaning of "buffer" in dm-integrity. Date: Sun, 4 Jun 2023 12:06:02 -0700 Message-Id: <20230604190604.4800-3-eatnumber1@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230604190604.4800-1-eatnumber1@gmail.com> References: <20230604190604.4800-1-eatnumber1@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org "Buffers" are buffers of the metadata/checksum area of dm-integrity. They are always at most as large as a single metadata area on-disk, but may be smaller. Signed-off-by: Russell Harmon --- .../admin-guide/device-mapper/dm-integrity.rst | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/Documentation/admin-guide/device-mapper/dm-integrity.rst b/Documentation/admin-guide/device-mapper/dm-integrity.rst index b2a698e955a3..31f514675809 100644 --- a/Documentation/admin-guide/device-mapper/dm-integrity.rst +++ b/Documentation/admin-guide/device-mapper/dm-integrity.rst @@ -38,6 +38,15 @@ the device. But it will only format the device if the superblock contains zeroes. If the superblock is neither valid nor zeroed, the dm-integrity target can't be loaded. +Accesses to the on-disk metadata area containing checksums (aka tags) are +buffered using dm-bufio. When an access to any given metadata area +occurs, each unique metadata area gets its own buffer(s). The buffer size +is capped at the size of the metadata area, but may be smaller, thereby +requiring multiple buffers to represent the full metadata area. A smaller +buffer size will produce a smaller resulting read/write operation to the +metadata area for small reads/writes. The metadata is still read even in +a full write to the data covered by a single buffer. + To use the target for the first time: 1. overwrite the superblock with zeroes @@ -106,10 +115,6 @@ buffer_sectors:number The number of sectors in one buffer. The value is rounded down to a power of two. - The tag area is accessed using buffers, the buffer size is - configurable. The large buffer size means that the I/O size will - be larger, but there could be less I/Os issued. - journal_watermark:number The journal watermark in percents. When the size of the journal exceeds this watermark, the thread that flushes the journal will -- 2.34.1