From patchwork Thu Aug 29 14:00:15 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paolo Bonzini X-Patchwork-Id: 270854 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [IPv6:2001:4830:134:3::11]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id E180F2C00AA for ; Fri, 30 Aug 2013 00:30:39 +1000 (EST) Received: from localhost ([::1]:43582 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VF2rW-0005ap-8k for incoming@patchwork.ozlabs.org; Thu, 29 Aug 2013 10:06:14 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:54111) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VF2mg-00079N-AW for qemu-devel@nongnu.org; Thu, 29 Aug 2013 10:01:22 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1VF2mX-0008BJ-Uc for qemu-devel@nongnu.org; Thu, 29 Aug 2013 10:01:14 -0400 Received: from mail-ea0-x22d.google.com ([2a00:1450:4013:c01::22d]:43992) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VF2mX-0008B5-Ft for qemu-devel@nongnu.org; Thu, 29 Aug 2013 10:01:05 -0400 Received: by mail-ea0-f173.google.com with SMTP id g10so267749eak.4 for ; Thu, 29 Aug 2013 07:01:04 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=sender:from:to:cc:subject:date:message-id:in-reply-to:references; bh=2nUXo9DbtWxBPVoV3oOXlEq30p2rdfyKfblzTJF5NEw=; b=VPBv///f/lje3YutIyPrrIR6lwNzE2SeRZMubR1m9uEV852Q+xot7woMHrN+In+l2e CrVStJDM/3I01m1w0/z5uXjaJujRhPHVwbNxnR0L+Xf+9oUXif5KLvX8HTShSrz0Zjah 67XwyHbOK/NzBK64Q01dSZ3rF9xvCltFyaWkxhd6d1Xru0+Yc0pIcbpqaKQQztkftRZ0 UAsnTtej3L1KCt6ss4WyAbY1lH2IsGugQ4KmDSVifLZ4CcKl+aO+hSvI098qjgyxHyJI dVfBwi0PhaYsZxh0m81OQkEih7yfol9BABk/k+jifV2wZoZKHx9yk5N49sPat/elpwRL pHZA== X-Received: by 10.15.56.72 with SMTP id x48mr41791eew.94.1377784864591; Thu, 29 Aug 2013 07:01:04 -0700 (PDT) Received: from yakj.usersys.redhat.com (nat-pool-mxp-t.redhat.com. [209.132.186.18]) by mx.google.com with ESMTPSA id p5sm46359028eeg.5.1969.12.31.16.00.00 (version=TLSv1.2 cipher=RC4-SHA bits=128/128); Thu, 29 Aug 2013 07:01:03 -0700 (PDT) From: Paolo Bonzini To: qemu-devel@nongnu.org Date: Thu, 29 Aug 2013 16:00:15 +0200 Message-Id: <1377784821-29561-16-git-send-email-pbonzini@redhat.com> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1377784821-29561-1-git-send-email-pbonzini@redhat.com> References: <1377784821-29561-1-git-send-email-pbonzini@redhat.com> X-detected-operating-system: by eggs.gnu.org: Error: Malformed IPv6 address (bad octet value). X-Received-From: 2a00:1450:4013:c01::22d Cc: kwolf@redhat.com, stefanha@redhat.com Subject: [Qemu-devel] [PATCH v4 15/21] block: return BDRV_BLOCK_ZERO past end of backing file X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org If the sectors are unallocated and we are past the end of the backing file, they will read as zero. Signed-off-by: Paolo Bonzini Reviewed-by: Eric Blake --- block.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-) diff --git a/block.c b/block.c index ecae287..cf52489 100644 --- a/block.c +++ b/block.c @@ -3028,8 +3028,16 @@ static int64_t coroutine_fn bdrv_co_get_block_status(BlockDriverState *bs, return ret; } - if (!(ret & BDRV_BLOCK_DATA) && bdrv_has_zero_init(bs)) { - ret |= BDRV_BLOCK_ZERO; + if (!(ret & BDRV_BLOCK_DATA)) { + if (bdrv_has_zero_init(bs)) { + ret |= BDRV_BLOCK_ZERO; + } else { + BlockDriverState *bs2 = bs->backing_hd; + int64_t length2 = bdrv_getlength(bs2); + if (length2 >= 0 && sector_num >= (length2 >> BDRV_SECTOR_BITS)) { + ret |= BDRV_BLOCK_ZERO; + } + } } return ret; }