From patchwork Thu Jun 8 11:56:25 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Fam Zheng X-Patchwork-Id: 772976 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)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 3wk3p14XL9z9s7B for ; Thu, 8 Jun 2017 21:57:45 +1000 (AEST) Received: from localhost ([::1]:48819 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dIw4N-0001c6-9V for incoming@patchwork.ozlabs.org; Thu, 08 Jun 2017 07:57:43 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:45984) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dIw3e-0001aG-H1 for qemu-devel@nongnu.org; Thu, 08 Jun 2017 07:56:59 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dIw3d-0001qV-Eo for qemu-devel@nongnu.org; Thu, 08 Jun 2017 07:56:58 -0400 Received: from mx1.redhat.com ([209.132.183.28]:44336) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1dIw3d-0001qO-4r for qemu-devel@nongnu.org; Thu, 08 Jun 2017 07:56:57 -0400 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 18449C0587E1; Thu, 8 Jun 2017 11:56:56 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 18449C0587E1 Authentication-Results: ext-mx08.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx08.extmail.prod.ext.phx2.redhat.com; spf=pass smtp.mailfrom=famz@redhat.com DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.redhat.com 18449C0587E1 Received: from lemon.redhat.com (ovpn-12-24.pek2.redhat.com [10.72.12.24]) by smtp.corp.redhat.com (Postfix) with ESMTP id C8F3B17DC9; Thu, 8 Jun 2017 11:56:54 +0000 (UTC) From: Fam Zheng To: qemu-devel@nongnu.org Date: Thu, 8 Jun 2017 19:56:25 +0800 Message-Id: <20170608115643.18859-6-famz@redhat.com> In-Reply-To: <20170608115643.18859-1-famz@redhat.com> References: <20170608115643.18859-1-famz@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.32]); Thu, 08 Jun 2017 11:56:56 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PULL v3 05/23] block: access copy_on_read with atomic ops 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: peter.maydell@linaro.org Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" From: Paolo Bonzini Reviewed-by: Stefan Hajnoczi Signed-off-by: Paolo Bonzini Message-Id: <20170605123908.18777-2-pbonzini@redhat.com> Signed-off-by: Fam Zheng --- block.c | 6 ++++-- block/io.c | 8 ++++---- blockdev.c | 2 +- include/block/block_int.h | 11 ++++++----- 4 files changed, 15 insertions(+), 12 deletions(-) diff --git a/block.c b/block.c index fa1d06d..af6366b 100644 --- a/block.c +++ b/block.c @@ -1300,7 +1300,9 @@ static int bdrv_open_common(BlockDriverState *bs, BlockBackend *file, goto fail_opts; } - assert(bs->copy_on_read == 0); /* bdrv_new() and bdrv_close() make it so */ + /* bdrv_new() and bdrv_close() make it so */ + assert(atomic_read(&bs->copy_on_read) == 0); + if (bs->open_flags & BDRV_O_COPY_ON_READ) { if (!bs->read_only) { bdrv_enable_copy_on_read(bs); @@ -3063,7 +3065,7 @@ static void bdrv_close(BlockDriverState *bs) g_free(bs->opaque); bs->opaque = NULL; - bs->copy_on_read = 0; + atomic_set(&bs->copy_on_read, 0); bs->backing_file[0] = '\0'; bs->backing_format[0] = '\0'; bs->total_sectors = 0; diff --git a/block/io.c b/block/io.c index ed31810..98c690f 100644 --- a/block/io.c +++ b/block/io.c @@ -130,13 +130,13 @@ void bdrv_refresh_limits(BlockDriverState *bs, Error **errp) */ void bdrv_enable_copy_on_read(BlockDriverState *bs) { - bs->copy_on_read++; + atomic_inc(&bs->copy_on_read); } void bdrv_disable_copy_on_read(BlockDriverState *bs) { - assert(bs->copy_on_read > 0); - bs->copy_on_read--; + int old = atomic_fetch_dec(&bs->copy_on_read); + assert(old >= 1); } /* Check if any requests are in-flight (including throttled requests) */ @@ -1144,7 +1144,7 @@ int coroutine_fn bdrv_co_preadv(BdrvChild *child, bdrv_inc_in_flight(bs); /* Don't do copy-on-read if we read data before write operation */ - if (bs->copy_on_read && !(flags & BDRV_REQ_NO_SERIALISING)) { + if (atomic_read(&bs->copy_on_read) && !(flags & BDRV_REQ_NO_SERIALISING)) { flags |= BDRV_REQ_COPY_ON_READ; } diff --git a/blockdev.c b/blockdev.c index 892d768..335fbcc 100644 --- a/blockdev.c +++ b/blockdev.c @@ -1791,7 +1791,7 @@ static void external_snapshot_commit(BlkActionState *common) /* We don't need (or want) to use the transactional * bdrv_reopen_multiple() across all the entries at once, because we * don't want to abort all of them if one of them fails the reopen */ - if (!state->old_bs->copy_on_read) { + if (!atomic_read(&state->old_bs->copy_on_read)) { bdrv_reopen(state->old_bs, state->old_bs->open_flags & ~BDRV_O_RDWR, NULL); } diff --git a/include/block/block_int.h b/include/block/block_int.h index cb78c4f..49f2ebb 100644 --- a/include/block/block_int.h +++ b/include/block/block_int.h @@ -595,11 +595,6 @@ struct BlockDriverState { /* Protected by AioContext lock */ - /* If true, copy read backing sectors into image. Can be >1 if more - * than one client has requested copy-on-read. - */ - int copy_on_read; - /* If we are reading a disk image, give its size in sectors. * Generally read-only; it is written to by load_snapshot and * save_snaphost, but the block layer is quiescent during those. @@ -633,6 +628,12 @@ struct BlockDriverState { QLIST_HEAD(, BdrvDirtyBitmap) dirty_bitmaps; + /* If true, copy read backing sectors into image. Can be >1 if more + * than one client has requested copy-on-read. Accessed with atomic + * ops. + */ + int copy_on_read; + /* do we need to tell the quest if we have a volatile write cache? */ int enable_write_cache;