From nobody Mon Feb 9 17:05:22 2026 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; dkim=fail; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail(p=none dis=none) header.from=redhat.com ARC-Seal: i=1; a=rsa-sha256; t=1607522191; cv=none; d=zohomail.com; s=zohoarc; b=FS4Nj8qEA/AgqAeF2/ImpOXRelcqBTo0DjwzQxOA316b0ZpnAFbarpVFZWYPXWBSgRlYRgIuJMApYNyI19zVEmnuSnToxMiauOSsE8pDicF5UM2Kd2jBAz763ENv0gr0XdGuXO6n896VCBreXXD6VIOR4xyukF4zSRMsoez4nPg= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1607522191; h=Content-Type:Content-Transfer-Encoding:Cc:Date:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:MIME-Version:Message-ID:References:Sender:Subject:To; bh=TTBlu82JM07TJK0WUoOslvbjwE7Y4wK55SOnPYWc4sc=; b=j+XBXbSlUWZoVcNPgFm1osUmCMHIG/cpw5/ZQCUW7jGeFjk78liqOAQXZaAeXO8ppfCaeum4L1kfvLG9pv13WIuaDEUHCJv65ayJB+GHnN/Fv/LI1ANeF1MNxHAJDbcnD78Zybjy5DXvD09eNcDQiXmjNHDXcw5ndJMC06JNVSc= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=fail; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail header.from= (p=none dis=none) header.from= Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1607522191292561.0835710104403; Wed, 9 Dec 2020 05:56:31 -0800 (PST) Received: from localhost ([::1]:40082 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kmzxE-0008Pd-6W for importer@patchew.org; Wed, 09 Dec 2020 08:56:29 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:34436) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kmzv7-0006lG-8G for qemu-devel@nongnu.org; Wed, 09 Dec 2020 08:54:17 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:30524) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1kmzv5-0000Kd-Kp for qemu-devel@nongnu.org; Wed, 09 Dec 2020 08:54:17 -0500 Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-178-tpeZ6fFbNkKC4iu842aSrg-1; Wed, 09 Dec 2020 08:54:12 -0500 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 547CA1005E4A; Wed, 9 Dec 2020 13:54:11 +0000 (UTC) Received: from localhost.localdomain (unknown [10.35.206.133]) by smtp.corp.redhat.com (Postfix) with ESMTP id 9A0955D6BA; Wed, 9 Dec 2020 13:54:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1607522054; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=TTBlu82JM07TJK0WUoOslvbjwE7Y4wK55SOnPYWc4sc=; b=Rtt40Zg/ZDhl/Pubu5BH17W1P2nSj0TfjzUVJT8NjMFhMiC98e4QBdUGyiOmmIF/wca4YH rSStlb8H0OioBVb677EnzS+H+vfAkDXT9X5PPzFlWbtj7G83pC8ce0pvm8WmSeYDmx8ET1 toNmyIHvN+AfzFM4SWLsjvHU+Bd8qZ4= X-MC-Unique: tpeZ6fFbNkKC4iu842aSrg-1 From: Maxim Levitsky To: qemu-devel@nongnu.org Subject: [PATCH v2 2/5] file-posix: add sg_get_max_segments that actually works with sg Date: Wed, 9 Dec 2020 15:53:52 +0200 Message-Id: <20201209135355.561745-3-mlevitsk@redhat.com> In-Reply-To: <20201209135355.561745-1-mlevitsk@redhat.com> References: <20201209135355.561745-1-mlevitsk@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=mlevitsk@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=63.128.21.124; envelope-from=mlevitsk@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Fam Zheng , Kevin Wolf , Ronnie Sahlberg , qemu-block@nongnu.org, Peter Lieven , Tom Yan , Stefan Hajnoczi , Paolo Bonzini , Maxim Levitsky , Max Reitz Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: fail (Header signature does not verify) Content-Type: text/plain; charset="utf-8" From: Tom Yan sg devices have different major/minor than their corresponding block devices. Using sysfs to get max segments never really worked for them. Fortunately the sg driver provides an ioctl to get sg_tablesize, which is apparently equivalent to max segments. Signed-off-by: Tom Yan Signed-off-by: Maxim Levitsky --- block/file-posix.c | 22 +++++++++++++++++++++- 1 file changed, 21 insertions(+), 1 deletion(-) diff --git a/block/file-posix.c b/block/file-posix.c index 226ddbbdad..10ebc4c5b7 100644 --- a/block/file-posix.c +++ b/block/file-posix.c @@ -1181,6 +1181,26 @@ static int sg_get_max_transfer_length(int fd) #endif } =20 +static int sg_get_max_segments(int fd) +{ + /* + * /dev/sg* character devices report 'max_segments' via + * SG_GET_SG_TABLESIZE ioctl + */ + +#ifdef SG_GET_SG_TABLESIZE + long max_segments =3D 0; + + if (ioctl(fd, SG_GET_SG_TABLESIZE, &max_segments) =3D=3D 0) { + return max_segments; + } else { + return -errno; + } +#else + return -ENOSYS; +#endif +} + static int get_max_transfer_length(int fd) { #if defined(BLKSECTGET) @@ -1267,7 +1287,7 @@ static void hdev_refresh_limits(BlockDriverState *bs,= Error **errp) bs->bl.max_transfer =3D pow2floor(ret); } =20 - ret =3D get_max_segments(s->fd); + ret =3D bs->sg ? sg_get_max_segments(s->fd) : get_max_segments(s->fd); if (ret > 0) { bs->bl.max_transfer =3D MIN_NON_ZERO(bs->bl.max_transfer, ret * qemu_real_host_page_size); --=20 2.26.2