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 9D2C7C77B73 for ; Mon, 5 Jun 2023 05:09:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232413AbjFEFJ1 (ORCPT ); Mon, 5 Jun 2023 01:09:27 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59382 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232165AbjFEFJY (ORCPT ); Mon, 5 Jun 2023 01:09:24 -0400 Received: from mail-il1-x134.google.com (mail-il1-x134.google.com [IPv6:2607:f8b0:4864:20::134]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AC924B1 for ; Sun, 4 Jun 2023 22:09:23 -0700 (PDT) Received: by mail-il1-x134.google.com with SMTP id e9e14a558f8ab-33b1da9a8acso22224955ab.3 for ; Sun, 04 Jun 2023 22:09:23 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20221208; t=1685941763; x=1688533763; 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=NIxZPq0dNPwwyqmLx/t7+TU07PeNHNWQegTRVDAf+qsMTvVAa57XuSQAv7oaUgolsz 4o1Rky3Q3lCBDArzo/wuQPs6MDX3vIFjGFYf/qQJDWjr785SQNHjSmHv05heOYOw98hp fzykSdlD/Vv5m9duRl1DNxnhD3kxPrXySAIQvsfmHtkMlWGigRGBrnc+0wUZfOR0VPMr m+KI8Jgj87sPCTpgDW/s8WsdpmpQsVw3oxyWneChNro3gkDWsjZ2JVS0N2/5CZXNdITV SiOyCyZZDLcmw+WO2ytU4cXAvRn87UOZIde8zwoaHX6gdxZk/Y0ikMwKwcWI1+88sgZf rxYQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1685941763; x=1688533763; 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=PIPkEf8H4vS89dHOoYRfEl++6T+ILw8E5xASXZJ5dSR/+9T8te+a4Y3E/Hsee+cLEq LmEuBwCBN0SEanGHutScNF0afOGIdYoPyw0ieNZee66PbGygonYGShRYgj9ClCfii8f7 xNhvBSRg0D5rIwY9AVe41x2+qhZT1SAizX2sDcDqfo3q7Ou8P+R+G2SCN7LhCxa+ryai iBUVSfAy0mvW2NMPW6C7pyWKy3k5XT12ZkD15gX6BKTpBzlao41UWpv/V7lBxg9SYalm L3dEUglGKBXJ243/MepLVBqPpUVgga1YJrDceWyKdANAOLAjq5B5Nqx+P6LQy5uBDzYB vwbw== X-Gm-Message-State: AC+VfDxDyCZe3EIbyApTi7y1UlDjsf/jsHFHImQ3v1fyWYuqa9SlW9ws EZyIxKUsjqS/SrwcP+iKrWeM6N2wgqnnkw== X-Google-Smtp-Source: ACHHUZ60cJPCU5c2Z31OTJ0Ltf0fy4A4LvBh+XDacnGy9xXs5a9nqxcHEjW8sk1BcPEujSTDrlHz1g== X-Received: by 2002:a92:cc11:0:b0:331:105c:81f9 with SMTP id s17-20020a92cc11000000b00331105c81f9mr19454579ilp.29.1685941762771; Sun, 04 Jun 2023 22:09:22 -0700 (PDT) Received: from localhost.localdomain ([76.132.108.20]) by smtp.gmail.com with ESMTPSA id fe16-20020a056a002f1000b0064d48d98260sm4329175pfb.156.2023.06.04.22.09.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 04 Jun 2023 22:09:22 -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 v4 2/4] Documentation: dm-integrity: Document the meaning of "buffer". Date: Sun, 4 Jun 2023 22:08:51 -0700 Message-Id: <20230605050853.6240-3-eatnumber1@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230605050853.6240-1-eatnumber1@gmail.com> References: <20230604190604.4800-1-eatnumber1@gmail.com> <20230605050853.6240-1-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 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 us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id D9D5AC7EE24 for ; Mon, 5 Jun 2023 05:09:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1685941774; h=from:from:sender:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:list-id:list-help: list-unsubscribe:list-subscribe:list-post; bh=d1y9FBS1cyOmL/Miu33/ho8IMBorm0qdYIuiModiKz8=; 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Custom Threat Dictionary=false X-Scanned-By: MIMEDefang 3.1 on 10.11.54.9 Subject: [dm-devel] [PATCH v4 2/4] Documentation: dm-integrity: Document the meaning of "buffer". X-BeenThere: dm-devel@redhat.com X-Mailman-Version: 2.1.29 Precedence: list List-Id: device-mapper development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Russell Harmon , dm-devel@redhat.com, mpatocka@redhat.com, snitzer@redhat.com, linux-doc@vger.kernel.org Errors-To: dm-devel-bounces@redhat.com Sender: "dm-devel" X-Scanned-By: MIMEDefang 3.1 on 10.11.54.8 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: gmail.com Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit "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 -- dm-devel mailing list dm-devel@redhat.com https://listman.redhat.com/mailman/listinfo/dm-devel