From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:44210) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cxP2o-0006VF-Au for qemu-devel@nongnu.org; Sun, 09 Apr 2017 22:27:09 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cxP2n-0007cj-Fc for qemu-devel@nongnu.org; Sun, 09 Apr 2017 22:27:06 -0400 From: Fam Zheng Date: Mon, 10 Apr 2017 10:26:36 +0800 Message-Id: <20170410022636.29925-3-famz@redhat.com> In-Reply-To: <20170410022636.29925-1-famz@redhat.com> References: <20170410022636.29925-1-famz@redhat.com> Subject: [Qemu-devel] [PATCH v3 2/2] block: Quiesce old aio context during bdrv_set_aio_context List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Paolo Bonzini , qemu-block@nongnu.org, Ed Swierk , Fam Zheng , Kevin Wolf , Max Reitz , Eric Blake , Stefan Hajnoczi The fact that the bs->aio_context is changing can confuse the dataplane iothread, because of the now fine granularity aio context lock. bdrv_drain should rather be a bdrv_drained_begin/end pair, but since bs->aio_context is changing, we can just use aio_disable_external and bdrv_parent_drained_begin. Reported-by: Ed Swierk Signed-off-by: Fam Zheng --- block.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/block.c b/block.c index b8a3011..a995a8e 100644 --- a/block.c +++ b/block.c @@ -4396,11 +4396,12 @@ void bdrv_attach_aio_context(BlockDriverState *bs, void bdrv_set_aio_context(BlockDriverState *bs, AioContext *new_context) { - AioContext *ctx; + AioContext *ctx = bdrv_get_aio_context(bs); + aio_disable_external(ctx); + bdrv_parent_drained_begin(bs); bdrv_drain(bs); /* ensure there are no in-flight requests */ - ctx = bdrv_get_aio_context(bs); while (aio_poll(ctx, false)) { /* wait for all bottom halves to execute */ } @@ -4412,6 +4413,8 @@ void bdrv_set_aio_context(BlockDriverState *bs, AioContext *new_context) */ aio_context_acquire(new_context); bdrv_attach_aio_context(bs, new_context); + bdrv_parent_drained_end(bs); + aio_enable_external(ctx); aio_context_release(new_context); } -- 2.9.3