From patchwork Thu May 7 14:45:13 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eric Blake X-Patchwork-Id: 283230 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.5 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E2B12C38A24 for ; Thu, 7 May 2020 14:46:29 +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 ACBD520575 for ; Thu, 7 May 2020 14:46:29 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="dIImAfmV" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org ACBD520575 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+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:40138 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jWhnA-0007uC-SN for qemu-devel@archiver.kernel.org; Thu, 07 May 2020 10:46:28 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:47486) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jWhmJ-00072N-Mx for qemu-devel@nongnu.org; Thu, 07 May 2020 10:45:36 -0400 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:21580 helo=us-smtp-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 1jWhmH-0003dR-Ty for qemu-devel@nongnu.org; Thu, 07 May 2020 10:45:35 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1588862732; 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=2mD0J+BqA3hH5L2MGfLPWpRGM1gavaMsHDS4Z1HMFV8=; b=dIImAfmVm4Hq5ztONVKR2f+yph+yoA7ayEsTEOfugcDgByZqRZ2+7j++x71qEPlyBj59dr IcU6dBYsrboTX1f1FYioYXVVNWSOCziFilNbfoY+qWR3x5cy0bWX05wSjhiqaC2XsS/ORM nydYzIkxqeY3BELUGdj55rxJBUeZP1s= 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-434-O-Z3v2kDNKCZoshuF8wnRA-1; Thu, 07 May 2020 10:45:29 -0400 X-MC-Unique: O-Z3v2kDNKCZoshuF8wnRA-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 2F867460; Thu, 7 May 2020 14:45:28 +0000 (UTC) Received: from blue.redhat.com (ovpn-114-73.phx2.redhat.com [10.3.114.73]) by smtp.corp.redhat.com (Postfix) with ESMTP id A86C15C1B0; Thu, 7 May 2020 14:45:24 +0000 (UTC) From: Eric Blake To: qemu-devel@nongnu.org Subject: [PATCH v2 10/9] qed: Simplify backing reads Date: Thu, 7 May 2020 09:45:13 -0500 Message-Id: <20200507144513.348470-1-eblake@redhat.com> In-Reply-To: <20200507084800.20596-1-vsementsov@virtuozzo.com> References: <20200507084800.20596-1-vsementsov@virtuozzo.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Received-SPF: pass client-ip=205.139.110.120; envelope-from=eblake@redhat.com; helo=us-smtp-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/05/07 03:15:48 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] 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_H2=-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, vsementsov@virtuozzo.com, "open list:qed" , stefanha@redhat.com, mreitz@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" The other four drivers that support backing files (qcow, qcow2, parallels, vmdk) all rely on the block layer to populate zeroes when reading beyond EOF of a short backing file. We can simplify the qed code by doing likewise. Signed-off-by: Eric Blake --- I noticed this during my audit that v1 of Vladimir's series was correct. No change in iotests results (test 274 is currently failing for qed, but for other reasons: +Traceback (most recent call last): + File "274", line 24, in + iotests.verify_image_format(supported_fmts=['qcow2']) +AttributeError: module 'iotests' has no attribute 'verify_image_format' ) block/qed.h | 1 - block/qed.c | 64 +++++------------------------------------------------ 2 files changed, 6 insertions(+), 59 deletions(-) diff --git a/block/qed.h b/block/qed.h index 42c115d8220c..3d12bf78d412 100644 --- a/block/qed.h +++ b/block/qed.h @@ -140,7 +140,6 @@ typedef struct QEDAIOCB { /* Current cluster scatter-gather list */ QEMUIOVector cur_qiov; - QEMUIOVector *backing_qiov; uint64_t cur_pos; /* position on block device, in bytes */ uint64_t cur_cluster; /* cluster offset in image file */ unsigned int cur_nclusters; /* number of clusters being accessed */ diff --git a/block/qed.c b/block/qed.c index 927382995a0c..bea4b9f6cc97 100644 --- a/block/qed.c +++ b/block/qed.c @@ -849,56 +849,18 @@ static BDRVQEDState *acb_to_s(QEDAIOCB *acb) * @s: QED state * @pos: Byte position in device * @qiov: Destination I/O vector - * @backing_qiov: Possibly shortened copy of qiov, to be allocated here - * @cb: Completion function - * @opaque: User data for completion function * * This function reads qiov->size bytes starting at pos from the backing file. * If there is no backing file then zeroes are read. */ static int coroutine_fn qed_read_backing_file(BDRVQEDState *s, uint64_t pos, - QEMUIOVector *qiov, - QEMUIOVector **backing_qiov) + QEMUIOVector *qiov) { - uint64_t backing_length = 0; - size_t size; - int ret; - - /* If there is a backing file, get its length. Treat the absence of a - * backing file like a zero length backing file. - */ if (s->bs->backing) { - int64_t l = bdrv_getlength(s->bs->backing->bs); - if (l < 0) { - return l; - } - backing_length = l; - } - - /* Zero all sectors if reading beyond the end of the backing file */ - if (pos >= backing_length || - pos + qiov->size > backing_length) { - qemu_iovec_memset(qiov, 0, 0, qiov->size); - } - - /* Complete now if there are no backing file sectors to read */ - if (pos >= backing_length) { - return 0; - } - - /* If the read straddles the end of the backing file, shorten it */ - size = MIN((uint64_t)backing_length - pos, qiov->size); - - assert(*backing_qiov == NULL); - *backing_qiov = g_new(QEMUIOVector, 1); - qemu_iovec_init(*backing_qiov, qiov->niov); - qemu_iovec_concat(*backing_qiov, qiov, 0, size); - - BLKDBG_EVENT(s->bs->file, BLKDBG_READ_BACKING_AIO); - ret = bdrv_co_preadv(s->bs->backing, pos, size, *backing_qiov, 0); - if (ret < 0) { - return ret; + BLKDBG_EVENT(s->bs->file, BLKDBG_READ_BACKING_AIO); + return bdrv_co_preadv(s->bs->backing, pos, qiov->size, qiov, 0); } + qemu_iovec_memset(qiov, 0, 0, qiov->size); return 0; } @@ -915,7 +877,6 @@ static int coroutine_fn qed_copy_from_backing_file(BDRVQEDState *s, uint64_t offset) { QEMUIOVector qiov; - QEMUIOVector *backing_qiov = NULL; int ret; /* Skip copy entirely if there is no work to do */ @@ -925,13 +886,7 @@ static int coroutine_fn qed_copy_from_backing_file(BDRVQEDState *s, qemu_iovec_init_buf(&qiov, qemu_blockalign(s->bs, len), len); - ret = qed_read_backing_file(s, pos, &qiov, &backing_qiov); - - if (backing_qiov) { - qemu_iovec_destroy(backing_qiov); - g_free(backing_qiov); - backing_qiov = NULL; - } + ret = qed_read_backing_file(s, pos, &qiov); if (ret) { goto out; @@ -1339,8 +1294,7 @@ static int coroutine_fn qed_aio_read_data(void *opaque, int ret, qemu_iovec_memset(&acb->cur_qiov, 0, 0, acb->cur_qiov.size); r = 0; } else if (ret != QED_CLUSTER_FOUND) { - r = qed_read_backing_file(s, acb->cur_pos, &acb->cur_qiov, - &acb->backing_qiov); + r = qed_read_backing_file(s, acb->cur_pos, &acb->cur_qiov); } else { BLKDBG_EVENT(bs->file, BLKDBG_READ_AIO); r = bdrv_co_preadv(bs->file, offset, acb->cur_qiov.size, @@ -1365,12 +1319,6 @@ static int coroutine_fn qed_aio_next_io(QEDAIOCB *acb) while (1) { trace_qed_aio_next_io(s, acb, 0, acb->cur_pos + acb->cur_qiov.size); - if (acb->backing_qiov) { - qemu_iovec_destroy(acb->backing_qiov); - g_free(acb->backing_qiov); - acb->backing_qiov = NULL; - } - acb->qiov_offset += acb->cur_qiov.size; acb->cur_pos += acb->cur_qiov.size; qemu_iovec_reset(&acb->cur_qiov);