From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="ZTDOdNL4" Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9E52AF0 for ; Sun, 3 Dec 2023 19:56:13 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1701662172; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=xNKUQpE6ACEyF1q91AK5Pa8cyyFRcdXFb2KIn9j+Qic=; b=ZTDOdNL4Ej95SNEAK13RgkV9ESUn+iltWoD1Ud3ZXYjuESJxBQEGt1gLOMUHY79FrWe+bW zmR9mKTTVwZRTn+KCM+Xq/CGYRmTRWqyp4YVi4NPf9eQBO6MntWr1ZD3chhpTca1GgUcyM EIUCP/e5o49k8jIeTbjDh3f+5/HMayE= Received: from mimecast-mx02.redhat.com (mx-ext.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-325-z5VdyYmhPpumcRg0ll2h0w-1; Sun, 03 Dec 2023 22:56:07 -0500 X-MC-Unique: z5VdyYmhPpumcRg0ll2h0w-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.rdu2.redhat.com [10.11.54.8]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 988FF3803515; Mon, 4 Dec 2023 03:56:06 +0000 (UTC) Received: from fedora (unknown [10.72.120.8]) by smtp.corp.redhat.com (Postfix) with ESMTPS id C4215C1596F; Mon, 4 Dec 2023 03:55:55 +0000 (UTC) Date: Mon, 4 Dec 2023 11:55:50 +0800 From: Ming Lei To: John Garry Cc: axboe@kernel.dk, kbusch@kernel.org, hch@lst.de, sagi@grimberg.me, jejb@linux.ibm.com, martin.petersen@oracle.com, djwong@kernel.org, viro@zeniv.linux.org.uk, brauner@kernel.org, chandan.babu@oracle.com, dchinner@redhat.com, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org, linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, tytso@mit.edu, jbongio@google.com, linux-api@vger.kernel.org Subject: Re: [PATCH 02/21] block: Limit atomic writes according to bio and queue limits Message-ID: References: <20230929102726.2985188-1-john.g.garry@oracle.com> <20230929102726.2985188-3-john.g.garry@oracle.com> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.8 On Mon, Dec 04, 2023 at 11:19:20AM +0800, Ming Lei wrote: > On Fri, Sep 29, 2023 at 10:27:07AM +0000, John Garry wrote: > > We rely the block layer always being able to send a bio of size > > atomic_write_unit_max without being required to split it due to request > > queue or other bio limits. > > > > A bio may contain min(BIO_MAX_VECS, limits->max_segments) vectors, > > and each vector is at worst case the device logical block size from > > direct IO alignment requirement. > > Both unit_max and unit_min are applied to FS bio, which is built over > single userspace buffer, so only the 1st and last vector can include Actually it isn't true for pwritev, and sorry for the noise. Thanks, Ming