From patchwork Tue Jul 7 14:46:29 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kevin Wolf X-Patchwork-Id: 11648845 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 9CBDA913 for ; Tue, 7 Jul 2020 14:47:31 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 34652206DF for ; Tue, 7 Jul 2020 14:47:31 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="W324qQbH" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 34652206DF Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Received: from localhost ([::1]:51964 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jsosc-0006Jr-2x for patchwork-qemu-devel@patchwork.kernel.org; Tue, 07 Jul 2020 10:47:30 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:39156) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jsorv-0005k7-7w for qemu-devel@nongnu.org; Tue, 07 Jul 2020 10:46:47 -0400 Received: from us-smtp-2.mimecast.com ([207.211.31.81]:47277 helo=us-smtp-delivery-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1jsorp-0007hT-7p for qemu-devel@nongnu.org; Tue, 07 Jul 2020 10:46:46 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1594133199; 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; bh=8uRqbq9+MGzTzxMr5ja7NLIkCymq/NQVdrEfBxzsaNI=; b=W324qQbHVPQrPVPfNx+m5RZl4deiWjCGxHTbZ7ad8qfjE/1zpKFoSRn6QGvRcBDsPEES4f 3QRV2SdIX1iHpdmXMmcASp2wIAv4O7zn+m0gigKAbndjZMZP0oxwxwBwwB0/9mt2foq5iL 32RcU8MPaoFp37ZvtnjUl6XKFMw2fD8= 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-513-hGipqnMGMciNUEmyxoNk1Q-1; Tue, 07 Jul 2020 10:46:38 -0400 X-MC-Unique: hGipqnMGMciNUEmyxoNk1Q-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id E69941005510; Tue, 7 Jul 2020 14:46:36 +0000 (UTC) Received: from linux.fritz.box.com (ovpn-114-113.ams2.redhat.com [10.36.114.113]) by smtp.corp.redhat.com (Postfix) with ESMTP id D1D5F5C1B2; Tue, 7 Jul 2020 14:46:33 +0000 (UTC) From: Kevin Wolf To: qemu-block@nongnu.org Subject: [PATCH] qemu-img map: Don't limit block status request size Date: Tue, 7 Jul 2020 16:46:29 +0200 Message-Id: <20200707144629.51235-1-kwolf@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=kwolf@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Received-SPF: pass client-ip=207.211.31.81; envelope-from=kwolf@redhat.com; helo=us-smtp-delivery-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/07/07 00:20:54 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -30 X-Spam_score: -3.1 X-Spam_bar: --- X-Spam_report: (-3.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1, 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_H3=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=_AUTOLEARN 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: kwolf@redhat.com, peter.maydell@linaro.org, qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" Limiting each loop iteration of qemu-img map to 1 GB was arbitrary from the beginning, though it only cut the maximum in half then because the interface a signed 32 bit byte count. These days, bdrv_block_status() supports a 64 bit byte count, so the arbitrary limit is even worse. On file-posix, bdrv_block_status() eventually maps to SEEK_HOLE and SEEK_DATA, which don't support a limit, but always do all of the work necessary to find the start of the next hole/data. Much of this work may be repeated if we don't use this information fully, but query with an only slightly larger offset in the next loop iteration. Therefore, if bdrv_block_status() is called in a loop, it should always pass the full number of bytes that the whole loop is interested in. This removes the arbitrary limit and speeds up 'qemu-img map' significantly on heavily fragmented images. Signed-off-by: Kevin Wolf Reviewed-by: Eric Blake --- qemu-img.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) diff --git a/qemu-img.c b/qemu-img.c index bdb9f6aa46..74946f81ca 100644 --- a/qemu-img.c +++ b/qemu-img.c @@ -3217,12 +3217,9 @@ static int img_map(int argc, char **argv) curr.start = start_offset; while (curr.start + curr.length < length) { int64_t offset = curr.start + curr.length; - int64_t n; + int64_t n = length - offset; - /* Probe up to 1 GiB at a time. */ - n = MIN(1 * GiB, length - offset); ret = get_block_status(bs, offset, n, &next); - if (ret < 0) { error_report("Could not read file metadata: %s", strerror(-ret)); goto out;