From patchwork Tue Aug 14 12:14:40 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: 957468 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (mailfrom) smtp.mailfrom=nongnu.org (client-ip=2001:4830:134:3::11; helo=lists.gnu.org; envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org; receiver=) Authentication-Results: ozlabs.org; dmarc=fail (p=none dis=none) header.from=virtuozzo.com Received: from lists.gnu.org (lists.gnu.org [IPv6:2001:4830:134:3::11]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 41qWlN12Mqz9sBJ for ; Tue, 14 Aug 2018 22:15:42 +1000 (AEST) Received: from localhost ([::1]:44022 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fpYEe-0002f1-Cw for incoming@patchwork.ozlabs.org; Tue, 14 Aug 2018 08:15:40 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:37590) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fpYDs-0002eD-Uq for qemu-devel@nongnu.org; Tue, 14 Aug 2018 08:14:54 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fpYDn-000528-Ri for qemu-devel@nongnu.org; Tue, 14 Aug 2018 08:14:52 -0400 Received: from relay.sw.ru ([185.231.240.75]:51088) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1fpYDn-000516-HB; Tue, 14 Aug 2018 08:14:47 -0400 Received: from vz-out.virtuozzo.com ([185.231.240.5] helo=kvm.sw.ru) by relay.sw.ru with esmtp (Exim 4.90_1) (envelope-from ) id 1fpYDk-0007K0-Ga; Tue, 14 Aug 2018 15:14:44 +0300 From: Vladimir Sementsov-Ogievskiy To: qemu-devel@nongnu.org, qemu-block@nongnu.org Date: Tue, 14 Aug 2018 15:14:40 +0300 Message-Id: <20180814121443.33114-6-vsementsov@virtuozzo.com> X-Mailer: git-send-email 2.11.1 In-Reply-To: <20180814121443.33114-1-vsementsov@virtuozzo.com> References: <20180814121443.33114-1-vsementsov@virtuozzo.com> X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x X-Received-From: 185.231.240.75 Subject: [Qemu-devel] [PATCH v3 5/8] block/mirror: fix and improve do_sync_target_write 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, famz@redhat.com, jcody@redhat.com, mreitz@redhat.com, den@openvz.org, pbonzini@redhat.com, jsnow@redhat.com Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" Use bdrv_dirty_bitmap_next_dirty_area() instead of bdrv_dirty_iter_next_area(), because of the following problems of bdrv_dirty_iter_next_area(): 1. Using HBitmap iterators we should carefully handle unaligned offset, as first call to hbitmap_iter_next() may return a value less than original offset (actually, it will be original offset rounded down to bitmap granularity). This handling is not done in do_sync_target_write(). 2. bdrv_dirty_iter_next_area() handles unaligned max_offset incorrectly: look at the code: if (max_offset == iter->bitmap->size) { /* If max_offset points to the image end, round it up by the * bitmap granularity */ gran_max_offset = ROUND_UP(max_offset, granularity); } else { gran_max_offset = max_offset; } ret = hbitmap_iter_next(&iter->hbi, false); if (ret < 0 || ret + granularity > gran_max_offset) { return false; } and assume that max_offset != iter->bitmap->size but still unaligned. if 0 < ret < max_offset we found dirty area, but the function can return false in this case (if ret + granularity > max_offset). 3. bdrv_dirty_iter_next_area() uses inefficient loop to find the end of the dirty area. Let's use more efficient hbitmap_next_zero instead (bdrv_dirty_bitmap_next_dirty_area() do so) Signed-off-by: Vladimir Sementsov-Ogievskiy --- block/mirror.c | 16 +++++++--------- 1 file changed, 7 insertions(+), 9 deletions(-) diff --git a/block/mirror.c b/block/mirror.c index b48c3f8cf5..d2806812c8 100644 --- a/block/mirror.c +++ b/block/mirror.c @@ -1167,25 +1167,22 @@ static void do_sync_target_write(MirrorBlockJob *job, MirrorMethod method, uint64_t offset, uint64_t bytes, QEMUIOVector *qiov, int flags) { - BdrvDirtyBitmapIter *iter; QEMUIOVector target_qiov; - uint64_t dirty_offset; - int dirty_bytes; + uint64_t dirty_offset = offset; + uint64_t dirty_bytes; if (qiov) { qemu_iovec_init(&target_qiov, qiov->niov); } - iter = bdrv_dirty_iter_new(job->dirty_bitmap); - bdrv_set_dirty_iter(iter, offset); - while (true) { bool valid_area; int ret; bdrv_dirty_bitmap_lock(job->dirty_bitmap); - valid_area = bdrv_dirty_iter_next_area(iter, offset + bytes, - &dirty_offset, &dirty_bytes); + valid_area = bdrv_dirty_bitmap_next_dirty_area( + job->dirty_bitmap, &dirty_offset, + MIN(offset + bytes, dirty_offset + INT_MAX), &dirty_bytes); if (!valid_area) { bdrv_dirty_bitmap_unlock(job->dirty_bitmap); break; @@ -1241,9 +1238,10 @@ static void do_sync_target_write(MirrorBlockJob *job, MirrorMethod method, break; } } + + dirty_offset += dirty_bytes; } - bdrv_dirty_iter_free(iter); if (qiov) { qemu_iovec_destroy(&target_qiov); }