From patchwork Tue Dec 11 16:43:14 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vladimir Sementsov-Ogievskiy X-Patchwork-Id: 10724199 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id A0E4B91E for ; Tue, 11 Dec 2018 16:54:15 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 905282B550 for ; Tue, 11 Dec 2018 16:54:15 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 8493E2B557; Tue, 11 Dec 2018 16:54:15 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 26F752B550 for ; Tue, 11 Dec 2018 16:54:15 +0000 (UTC) Received: from localhost ([::1]:40088 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gWlIU-0002d1-Ax for patchwork-qemu-devel@patchwork.kernel.org; Tue, 11 Dec 2018 11:54:14 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:42054) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gWl85-0001u6-CG for qemu-devel@nongnu.org; Tue, 11 Dec 2018 11:43:30 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gWl82-0004Id-8I for qemu-devel@nongnu.org; Tue, 11 Dec 2018 11:43:29 -0500 Received: from relay.sw.ru ([185.231.240.75]:47264) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1gWl81-0004DQ-SO; Tue, 11 Dec 2018 11:43:26 -0500 Received: from [10.28.8.145] (helo=kvm.sw.ru) by relay.sw.ru with esmtp (Exim 4.91) (envelope-from ) id 1gWl7v-0001lo-P3; Tue, 11 Dec 2018 19:43:19 +0300 From: Vladimir Sementsov-Ogievskiy To: qemu-devel@nongnu.org, qemu-block@nongnu.org Date: Tue, 11 Dec 2018 19:43:14 +0300 Message-Id: <20181211164317.32893-6-vsementsov@virtuozzo.com> X-Mailer: git-send-email 2.18.0 In-Reply-To: <20181211164317.32893-1-vsementsov@virtuozzo.com> References: <20181211164317.32893-1-vsementsov@virtuozzo.com> X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x [fuzzy] X-Received-From: 185.231.240.75 Subject: [Qemu-devel] [PATCH v2 5/8] qcow2: qcow2_co_preadv: improve locking X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kwolf@redhat.com, vsementsov@virtuozzo.com, berto@igalia.com, mreitz@redhat.com, den@openvz.org Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" X-Virus-Scanned: ClamAV using ClamSMTP Background: decryption will be done in threads, to take benefit of it, we should move it out of the lock first. But let's go further: it turns out, that for locking around switch cases we have only two variants: when we just do memset(0) not releasing the lock (it is useless) and when we actually can handle the whole case out of the lock. So, refactor the whole thing to reduce locked code region and make it clean. Signed-off-by: Vladimir Sementsov-Ogievskiy --- block/qcow2.c | 48 ++++++++++++++++++++++++------------------------ 1 file changed, 24 insertions(+), 24 deletions(-) diff --git a/block/qcow2.c b/block/qcow2.c index c4b716d4f6..2a49314e42 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -1884,6 +1884,7 @@ static coroutine_fn int qcow2_co_preadv(BlockDriverState *bs, uint64_t offset, ret = qcow2_get_cluster_offset(bs, offset, &cur_bytes, &cluster_offset); if (ret < 0) { + qemu_co_mutex_unlock(&s->lock); goto fail; } @@ -1892,39 +1893,38 @@ static coroutine_fn int qcow2_co_preadv(BlockDriverState *bs, uint64_t offset, qemu_iovec_reset(&hd_qiov); qemu_iovec_concat(&hd_qiov, qiov, bytes_done, cur_bytes); + if (ret == QCOW2_CLUSTER_ZERO_PLAIN || + ret == QCOW2_CLUSTER_ZERO_ALLOC || + (ret == QCOW2_CLUSTER_UNALLOCATED && !bs->backing)) + { + /* No sense in releasing the lock */ + + qemu_iovec_memset(&hd_qiov, 0, 0, cur_bytes); + + bytes -= cur_bytes; + offset += cur_bytes; + bytes_done += cur_bytes; + continue; + } + + qemu_co_mutex_unlock(&s->lock); + switch (ret) { case QCOW2_CLUSTER_UNALLOCATED: - - if (bs->backing) { - BLKDBG_EVENT(bs->file, BLKDBG_READ_BACKING_AIO); - qemu_co_mutex_unlock(&s->lock); - ret = bdrv_co_preadv(bs->backing, offset, cur_bytes, - &hd_qiov, 0); - qemu_co_mutex_lock(&s->lock); - if (ret < 0) { - goto fail; - } - } else { - /* Note: in this case, no need to wait */ - qemu_iovec_memset(&hd_qiov, 0, 0, cur_bytes); + BLKDBG_EVENT(bs->file, BLKDBG_READ_BACKING_AIO); + ret = bdrv_co_preadv(bs->backing, offset, cur_bytes, &hd_qiov, 0); + if (ret < 0) { + goto fail; } break; - case QCOW2_CLUSTER_ZERO_PLAIN: - case QCOW2_CLUSTER_ZERO_ALLOC: - qemu_iovec_memset(&hd_qiov, 0, 0, cur_bytes); - break; - case QCOW2_CLUSTER_COMPRESSED: - qemu_co_mutex_unlock(&s->lock); ret = qcow2_co_preadv_compressed(bs, cluster_offset, offset, cur_bytes, &hd_qiov); - qemu_co_mutex_lock(&s->lock); if (ret < 0) { goto fail; } - break; case QCOW2_CLUSTER_NORMAL: @@ -1957,11 +1957,9 @@ static coroutine_fn int qcow2_co_preadv(BlockDriverState *bs, uint64_t offset, } BLKDBG_EVENT(bs->file, BLKDBG_READ_AIO); - qemu_co_mutex_unlock(&s->lock); ret = bdrv_co_preadv(bs->file, cluster_offset + offset_in_cluster, cur_bytes, &hd_qiov, 0); - qemu_co_mutex_lock(&s->lock); if (ret < 0) { goto fail; } @@ -1992,12 +1990,14 @@ static coroutine_fn int qcow2_co_preadv(BlockDriverState *bs, uint64_t offset, bytes -= cur_bytes; offset += cur_bytes; bytes_done += cur_bytes; + + qemu_co_mutex_lock(&s->lock); } ret = 0; -fail: qemu_co_mutex_unlock(&s->lock); +fail: qemu_iovec_destroy(&hd_qiov); qemu_vfree(cluster_data);