From nobody Tue Feb 10 03:39:43 2026 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; dkim=fail header.i=@wdc.com; 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=wdc.com ARC-Seal: i=1; a=rsa-sha256; t=1597186377; cv=none; d=zohomail.com; s=zohoarc; b=LhF6tKF0+2bfU5Yk90rxhpZ3XEDm1WjSAmUXzR186MShc16l+XuAd+uooF5DC3o2yEqcHj7BrwpHUKzryHHf5C3k9u6itsIGEki56LCWQua/DaOKXjjn2AvOreEUZUwiHMplrECy3tvEVp204qmrNkNWHPi8FY+AstZJHMp2pDw= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1597186377; h=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=n+2en078IuUYgv0txetz0RK0iSiXnElA9g+mjW/mCoE=; b=YXJmFgtOHtH8s70IZeqB8v93dWYXoaj/ehHRlFQh9el/WLqNHtMjcWD+PumOhoMb6bKAo00YjH8wa6ZecM8mhTJDVARkTIhNEBrFuvIO9Jb5lHYUgAHZvOLrhqaoZipZbctTHDPQuS9/PlT92x6xTF7P6MQ3PYCo22T/bElWKfM= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=fail header.i=@wdc.com; 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 1597186377799990.2161436312425; Tue, 11 Aug 2020 15:52:57 -0700 (PDT) Received: from localhost ([::1]:33502 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1k5d8a-0003M8-Ee for importer@patchew.org; Tue, 11 Aug 2020 18:52:56 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:40544) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1k5d7I-0001xD-S7; Tue, 11 Aug 2020 18:51:37 -0400 Received: from esa4.hgst.iphmx.com ([216.71.154.42]:19425) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1k5d7G-0004NG-F6; Tue, 11 Aug 2020 18:51:36 -0400 Received: from h199-255-45-15.hgst.com (HELO uls-op-cesaep02.wdc.com) ([199.255.45.15]) by ob1.hgst.iphmx.com with ESMTP; 12 Aug 2020 06:51:31 +0800 Received: from uls-op-cesaip02.wdc.com ([10.248.3.37]) by uls-op-cesaep02.wdc.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 11 Aug 2020 15:38:41 -0700 Received: from unknown (HELO redsun50.ssa.fujisawa.hgst.com) ([10.149.66.24]) by uls-op-cesaip02.wdc.com with ESMTP; 11 Aug 2020 15:51:29 -0700 DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=wdc.com; i=@wdc.com; q=dns/txt; s=dkim.wdc.com; t=1597186294; x=1628722294; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=2W3FRATOlz7ZU5eCO7umucqwcVhGX67USiGo9cGzhHg=; b=b8IMHkfYfUao9BdAsTGbTWC59qg3zyWIQfk97sHyvZ7RckQfwE99cLbH HCdAR2IfxVoeHpmig5+KZ0g141XV+IamTrU8Lj2NMdxEdFHMX/wfwjYDY yDyfETplAILBNvsPJ+8IbEUhFi1yDxtJyCqPT0sCYoMYsSRGDQvpOScLR 1aJlnsdXxo3RvDdWlWsgXvbZMicmm2RWbIxszv+9TSP3p/jOtHeTHjnx6 2KRVc4RpNQUkFBFmZk4DC2Thj3UQ4sIM1kPRCy8HUscTodkv/vOHxogNv azIo8WWT0niPJTzrmUZ8+fMI7hnfJKRGDuZLlNZUtJBD/8WIc0GnyHZ9y Q==; IronPort-SDR: PzPjjWy0KkBvUg7Z0ALcYXjRsJkoEW6KnEQ8l51abMRh9BHCyCqgddbmWsCmU+Yu2b3pxwR+9+ +v64SqnsTTQLV/BTIAhCiZ3R/X2PYdNZ5okR2DGnx8Y0E81U5Qg7bGA7b3t5RaKYr9LyZFnOa4 GEDpAW18yRpRLW7T5A6UmoswlNh+Pr8KFDPCEuibmrW8DSaMI8WG4jRt/JpufxNuZHRsGk27C/ znrFDlw85mfZDvqncItSw0Vobv8ckHU69bQyg9eIL59d8tFefvFbFDDbmX4n8B+yIuo2uezOOU W8w= X-IronPort-AV: E=Sophos;i="5.76,302,1592841600"; d="scan'208";a="144706609" IronPort-SDR: yDIVFSOWRTtQkEHkzmuWw57WTRAmrwOAwjrB3VtUTk2dM4SO3+KUUagpiotrhgUNtcTIBCxBFa +2qy39/cC5Tw== IronPort-SDR: N8N0KnRAvyiDG5tTeQRckcWx2WEav6ah2uPp5BTPZMNrNAvel9QoMx1r+vTP0EYv0rMh9wnLkG mVxMggf0vIGQ== WDCIronportException: Internal From: Dmitry Fomichev To: Kevin Wolf , Max Reitz , Paolo Bonzini , Fam Zheng , Maxim Levitsky , =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= Subject: [PATCH 1/2] file-posix: Correctly read max_segments of SG nodes Date: Wed, 12 Aug 2020 07:51:21 +0900 Message-Id: <20200811225122.17342-2-dmitry.fomichev@wdc.com> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20200811225122.17342-1-dmitry.fomichev@wdc.com> References: <20200811225122.17342-1-dmitry.fomichev@wdc.com> MIME-Version: 1.0 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=216.71.154.42; envelope-from=prvs=485daf1e4=dmitry.fomichev@wdc.com; helo=esa4.hgst.iphmx.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/08/11 18:51:29 X-ACL-Warn: Detected OS = FreeBSD 9.x or newer [fuzzy] X-Spam_score_int: -43 X-Spam_score: -4.4 X-Spam_bar: ---- X-Spam_report: (-4.4 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_MED=-2.3, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001, URIBL_BLOCKED=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: Dmitry Fomichev , Damien Le Moal , Alistair Francis , qemu-devel@nongnu.org, qemu-block@nongnu.org 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" If scsi-generic driver is in use, an SG node can be specified in the command line in place of a regular SCSI device. In this case, sg_get_max_segments() fails to open max_segments entry in sysfs because /dev/sgX is a character device. As the result, the maximum transfer size for the device may be calculated incorrectly, causing I/O errors if the maximum transfer size at the guest ends up to be larger compared to the host. Check system device type in sg_get_max_segments() and read the max_segments value differently if it is a character device. Reported-by: Johannes Thumshirn Fixes: 9103f1ceb46614b150bcbc3c9a4fbc72b47fedcc Signed-off-by: Dmitry Fomichev --- block/file-posix.c | 55 +++++++++++++++++++++++++++------------------- 1 file changed, 32 insertions(+), 23 deletions(-) diff --git a/block/file-posix.c b/block/file-posix.c index 094e3b0212..f9e2424e8f 100644 --- a/block/file-posix.c +++ b/block/file-posix.c @@ -1108,6 +1108,7 @@ static int sg_get_max_segments(int fd) int ret; int sysfd =3D -1; long max_segments; + unsigned int max_segs; struct stat st; =20 if (fstat(fd, &st)) { @@ -1115,30 +1116,38 @@ static int sg_get_max_segments(int fd) goto out; } =20 - sysfspath =3D g_strdup_printf("/sys/dev/block/%u:%u/queue/max_segments= ", - major(st.st_rdev), minor(st.st_rdev)); - sysfd =3D open(sysfspath, O_RDONLY); - if (sysfd =3D=3D -1) { - ret =3D -errno; - goto out; + if (S_ISBLK(st.st_mode)) { + sysfspath =3D g_strdup_printf("/sys/dev/block/%u:%u/queue/max_segm= ents", + major(st.st_rdev), minor(st.st_rdev)); + sysfd =3D open(sysfspath, O_RDONLY); + if (sysfd =3D=3D -1) { + ret =3D -errno; + goto out; + } + do { + ret =3D read(sysfd, buf, sizeof(buf) - 1); + } while (ret =3D=3D -1 && errno =3D=3D EINTR); + if (ret < 0) { + ret =3D -errno; + goto out; + } else if (ret =3D=3D 0) { + ret =3D -EIO; + goto out; + } + buf[ret] =3D 0; + /* The file is ended with '\n', pass 'end' to accept that. */ + ret =3D qemu_strtol(buf, &end, 10, &max_segments); + if (ret =3D=3D 0 && end && *end =3D=3D '\n') { + ret =3D max_segments; + } + } else { + ret =3D ioctl(fd, SG_GET_SG_TABLESIZE, &max_segs); + if (ret !=3D 0) { + ret =3D -errno; + goto out; + } + ret =3D max_segs; } - do { - ret =3D read(sysfd, buf, sizeof(buf) - 1); - } while (ret =3D=3D -1 && errno =3D=3D EINTR); - if (ret < 0) { - ret =3D -errno; - goto out; - } else if (ret =3D=3D 0) { - ret =3D -EIO; - goto out; - } - buf[ret] =3D 0; - /* The file is ended with '\n', pass 'end' to accept that. */ - ret =3D qemu_strtol(buf, &end, 10, &max_segments); - if (ret =3D=3D 0 && end && *end =3D=3D '\n') { - ret =3D max_segments; - } - out: if (sysfd !=3D -1) { close(sysfd); --=20 2.21.0