From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 61143606A31C for ; Fri, 13 Nov 2026 10:30:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.a=rsa-sha256 header.s=bombadil.20210309 header.b=qHfOUAHJ; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=LtqXe8qJ DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Type:MIME-Version: References:In-Reply-To:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Unsubscribe-Post:List-Owner; bh=YVyO34/+vwkp8pkrCOkfsJrmVw+ShcRwN5uH3EK9AOQ=; b=qHfOUAHJt98OqbCzwOdGq5PymS UZNHwSnQY0rivoOv0Pl6kvaT7dyWvzqSaV1CvIzedKpncAoTBgWa0QNfTOWSPLDLepwE8Ddw9nT/P 1eNhuWJNGG7/hCkVA3mG90Hk/5MD/oTZx2B76qTym7AokQYiWXrRO3nlK68sVTfCtASYyNwol6vUx Fqa6Xa4iEhP1eh9Bvrpxnkn995OP1jChIqocMrSNYJ0noFKsMYhFhqAkpVtuv+aTY4Sjd/2fikxEk ItVnUT65EbArlc11vqQSV0SCF/+eEixuyYWl3r1jblC0cJDb72aFN8yZ8L4Dk9RW29KWQ0zs1UFvy lPoXoGvA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.100.1 #2 (Red Hat Linux)) id 1xRoYX-0000000CNFX-0cXu; Fri, 13 Nov 2026 10:30:53 +0000 Received: from tor.source.kernel.org ([2600:3c04:e001:324:0:1991:8:25]) by bombadil.infradead.org with esmtps (Exim 4.100.1 #2 (Red Hat Linux)) id 1xRoYV-0000000CNFH-3Q0a for linux-nvme@lists.infradead.org; Fri, 13 Nov 2026 10:30:51 +0000 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id 113D36258B; Fri, 13 Nov 2026 10:30:51 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id F2B041F000C4; Fri, 13 Nov 2026 10:30:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794565850; bh=YVyO34/+vwkp8pkrCOkfsJrmVw+ShcRwN5uH3EK9AOQ=; h=Date:From:To:Cc:Subject:In-Reply-To:References; b=LtqXe8qJjoCs6EgAPAbRpq91b52a2VyeQM1Gmbh1aszCIQsHw90zu2II0XhvZBVPf MYe4sCeWsUIT4Qk1u+8y141B9pvooL1UVPFd4jVeuj583/dWSS0d8wIZXTRqeo8Cmr jX0clMTXPzsOgqjpxbfc1oq46h+KocQFM3MQ934rxvl7SR7DdRoDmc6Oxb3/xmKe2C wl8K8UDU/hOCVkeESaZt2xwyECXACM3PlylmDK3o568qfqNsFmFKM3uzFK4Va3DPl2 ljQeGJWVYW2W0/PMV9BcmlO9j3pNwLvEEUbnzib0+EcpdDyUPufXUZKKoMr92Uz2ED 0eedJIL8aZeJQ== Date: Fri, 13 Nov 2026 11:30:34 +0100 From: Daniel Gomez To: Arthur Simchaev Cc: Jens Axboe , Keith Busch , Christoph Hellwig , Sagi Grimberg , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org, Andres Freund , Pankaj Raghav , GOST , Daniel Gomez , Avi.Shchislowski@sandisk.com, Alex.Lemberg@sandisk.com Subject: Re: [PATCH RFC 1/2] block: add BLK_FEAT_ATOMIC_WRITE_MULTI Message-ID: <20261113103711.1-da.gomez@kernel.org> In-Reply-To: <20261103093849.203851-1-arthur.simchaev@sandisk.com> References: <20260929-nvme-mam-v1-1-48dcbe79cece@samsung.com> <20261103093849.203851-1-arthur.simchaev@sandisk.com> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 X-Mailer: lorebird X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-nvme" X-Spam-Status: No, score=-10.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On 2026-11-03T11:38:49+02:00, Arthur Simchaev wrote: > On Tue, Sep 29, 2026 at 01:17:11PM +0200, Daniel Gomez wrote: > [...] > > diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h > > index d003a9d2d1f6c..92efd4ff67f26 100644 > > --- a/include/linux/blkdev.h > > +++ b/include/linux/blkdev.h > > @@ -360,6 +360,9 @@ typedef unsigned int __bitwise blk_features_t; > > #define BLK_FEAT_RAID_PARTIAL_STRIPES_EXPENSIVE \ > > ((__force blk_features_t)(1u << 15)) > > > > +/* device writes each atomic write boundary window of a command atomically */ > > +#define BLK_FEAT_ATOMIC_WRITE_MULTI ((__force blk_features_t)(1u << 16)) > > With this flag set, a request with REQ_ATOMIC may now carry several independent > atomic writes rather than one. Code that looks at REQ_ATOMIC on a request (e.g. > blk_insert_cloned_request(), or a future SCSI WRITE ATOMIC user) needs to know > that. Could the comment here (or Documentation/block/) spell out what REQ_ATOMIC > means on a merged request, and what a driver must guarantee before setting the > flag? Makes sense. I'll update accordingly on both places. > > It might also be useful to expose the feature in sysfs next to the other > atomic_write_* attributes, so users can tell whether merging across boundaries > is active on a device. TBH, I was initially hesitant with the idea of adding another attribute. I'll add it and if we find it not useful we can drop it during review time.