From patchwork Fri Apr 28 12:39:45 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stefan Hajnoczi X-Patchwork-Id: 13226416 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 23948C77B60 for ; Fri, 28 Apr 2023 12:41:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346076AbjD1MlI (ORCPT ); Fri, 28 Apr 2023 08:41:08 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41606 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1346062AbjD1MlG (ORCPT ); Fri, 28 Apr 2023 08:41:06 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4F6153AB6 for ; Fri, 28 Apr 2023 05:40:21 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1682685620; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=kNO7bUwm9cBK4+CqxMAaVkrctpqeObAqrTqFbWZjZlA=; b=h5yqDlAhOgHtuCiGpB1Hl2LQTpMFeSuLM5DZEOFb19dVRP5Yl1UijxUd9RxWi+GmZ22iv9 v2iWyRXM9ZTYki75SoAI6Ezi8Ie1hoKYkYTmhxZeMafR/cJ9cgJhhFcrpox90I3+8u+x9j Wj/0JISqOOOBaxwCytng97wE03U4740= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-484-ThCvfjjsPyy0PXtlOH5dCA-1; Fri, 28 Apr 2023 08:40:19 -0400 X-MC-Unique: ThCvfjjsPyy0PXtlOH5dCA-1 Received: from smtp.corp.redhat.com (int-mx10.intmail.prod.int.rdu2.redhat.com [10.11.54.10]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 083583C0E46C; Fri, 28 Apr 2023 12:40:18 +0000 (UTC) Received: from localhost (unknown [10.39.192.223]) by smtp.corp.redhat.com (Postfix) with ESMTP id 77E224021B9; Fri, 28 Apr 2023 12:40:17 +0000 (UTC) From: Stefan Hajnoczi To: qemu-devel@nongnu.org Cc: Thomas Huth , =?utf-8?q?Daniel_P=2E_Berrang=C3=A9?= , Raphael Norwitz , Julia Suvorova , Cornelia Huck , Eric Blake , Paolo Bonzini , Aarushi Mehta , Stefan Hajnoczi , Richard Henderson , Kevin Wolf , Markus Armbruster , Stefano Garzarella , qemu-block@nongnu.org, Hanna Reitz , Fam Zheng , =?utf-8?q?Marc?= =?utf-8?q?-Andr=C3=A9_Lureau?= , "Michael S. Tsirkin" , kvm@vger.kernel.org, =?utf-8?q?Phili?= =?utf-8?q?ppe_Mathieu-Daud=C3=A9?= , Sam Li , Damien Le Moal , Dmitry Fomichev Subject: [PULL 08/17] docs/zoned-storage: add zoned device documentation Date: Fri, 28 Apr 2023 08:39:45 -0400 Message-Id: <20230428123954.179035-9-stefanha@redhat.com> In-Reply-To: <20230428123954.179035-1-stefanha@redhat.com> References: <20230428123954.179035-1-stefanha@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.10 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org From: Sam Li Add the documentation about the zoned device support to virtio-blk emulation. Signed-off-by: Sam Li Reviewed-by: Stefan Hajnoczi Reviewed-by: Damien Le Moal Reviewed-by: Dmitry Fomichev Acked-by: Kevin Wolf Signed-off-by: Stefan Hajnoczi Message-id: 20230427172019.3345-9-faithilikerun@gmail.com Message-id: 20230324090605.28361-9-faithilikerun@gmail.com [Add index-api.rst to fix "zoned-storage.rst:document isn't included in any toctree" error and fix pre-formatted command-line indentation. --Stefan] Signed-off-by: Stefan Hajnoczi --- docs/devel/index-api.rst | 1 + docs/devel/zoned-storage.rst | 43 ++++++++++++++++++++++++++ docs/system/qemu-block-drivers.rst.inc | 6 ++++ 3 files changed, 50 insertions(+) create mode 100644 docs/devel/zoned-storage.rst diff --git a/docs/devel/index-api.rst b/docs/devel/index-api.rst index 60c0d7459d..7108821746 100644 --- a/docs/devel/index-api.rst +++ b/docs/devel/index-api.rst @@ -12,3 +12,4 @@ generated from in-code annotations to function prototypes. memory modules ui + zoned-storage diff --git a/docs/devel/zoned-storage.rst b/docs/devel/zoned-storage.rst new file mode 100644 index 0000000000..da78db2783 --- /dev/null +++ b/docs/devel/zoned-storage.rst @@ -0,0 +1,43 @@ +============= +zoned-storage +============= + +Zoned Block Devices (ZBDs) divide the LBA space into block regions called zones +that are larger than the LBA size. They can only allow sequential writes, which +can reduce write amplification in SSDs, and potentially lead to higher +throughput and increased capacity. More details about ZBDs can be found at: + +https://zonedstorage.io/docs/introduction/zoned-storage + +1. Block layer APIs for zoned storage +------------------------------------- +QEMU block layer supports three zoned storage models: +- BLK_Z_HM: The host-managed zoned model only allows sequential writes access +to zones. It supports ZBD-specific I/O commands that can be used by a host to +manage the zones of a device. +- BLK_Z_HA: The host-aware zoned model allows random write operations in +zones, making it backward compatible with regular block devices. +- BLK_Z_NONE: The non-zoned model has no zones support. It includes both +regular and drive-managed ZBD devices. ZBD-specific I/O commands are not +supported. + +The block device information resides inside BlockDriverState. QEMU uses +BlockLimits struct(BlockDriverState::bl) that is continuously accessed by the +block layer while processing I/O requests. A BlockBackend has a root pointer to +a BlockDriverState graph(for example, raw format on top of file-posix). The +zoned storage information can be propagated from the leaf BlockDriverState all +the way up to the BlockBackend. If the zoned storage model in file-posix is +set to BLK_Z_HM, then block drivers will declare support for zoned host device. + +The block layer APIs support commands needed for zoned storage devices, +including report zones, four zone operations, and zone append. + +2. Emulating zoned storage controllers +-------------------------------------- +When the BlockBackend's BlockLimits model reports a zoned storage device, users +like the virtio-blk emulation or the qemu-io-cmds.c utility can use block layer +APIs for zoned storage emulation or testing. + +For example, to test zone_report on a null_blk device using qemu-io is:: + + $ path/to/qemu-io --image-opts -n driver=host_device,filename=/dev/nullb0 -c "zrp offset nr_zones" diff --git a/docs/system/qemu-block-drivers.rst.inc b/docs/system/qemu-block-drivers.rst.inc index dfe5d2293d..105cb9679c 100644 --- a/docs/system/qemu-block-drivers.rst.inc +++ b/docs/system/qemu-block-drivers.rst.inc @@ -430,6 +430,12 @@ Hard disks you may corrupt your host data (use the ``-snapshot`` command line option or modify the device permissions accordingly). +Zoned block devices + Zoned block devices can be passed through to the guest if the emulated storage + controller supports zoned storage. Use ``--blockdev host_device, + node-name=drive0,filename=/dev/nullb0,cache.direct=on`` to pass through + ``/dev/nullb0`` as ``drive0``. + Windows ^^^^^^^