From patchwork Fri Oct 9 05:45:20 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Fam Zheng X-Patchwork-Id: 528263 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from eggs.gnu.org (eggs.gnu.org [IPv6:2001:4830:134:3::10]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 92DFA1402B4 for ; Sat, 10 Oct 2015 02:30:10 +1100 (AEDT) Received: from lists.gnu.org ([208.118.235.17]:46205) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZkZcW-0001sX-KQ for incoming@patchwork.ozlabs.org; Fri, 09 Oct 2015 11:30:08 -0400 Received: from localhost ([::1]:39214 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZkZcW-0006im-Gj for incoming@patchwork.ozlabs.org; Fri, 09 Oct 2015 11:30:08 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:40173) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZkQV9-0000BB-Hc for qemu-devel@nongnu.org; Fri, 09 Oct 2015 01:45:56 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZkQV8-0003CV-Hz for qemu-devel@nongnu.org; Fri, 09 Oct 2015 01:45:55 -0400 Received: from mx1.redhat.com ([209.132.183.28]:35131) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZkQV6-0003C2-Eu; Fri, 09 Oct 2015 01:45:52 -0400 Received: from int-mx14.intmail.prod.int.phx2.redhat.com (int-mx14.intmail.prod.int.phx2.redhat.com [10.5.11.27]) by mx1.redhat.com (Postfix) with ESMTPS id 23EEDB4C4A; Fri, 9 Oct 2015 05:45:52 +0000 (UTC) Received: from cpc-pc.redhat.com (vpn1-7-191.pek2.redhat.com [10.72.7.191]) by int-mx14.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id t995jIgp027141; Fri, 9 Oct 2015 01:45:48 -0400 From: Fam Zheng To: qemu-devel@nongnu.org Date: Fri, 9 Oct 2015 13:45:20 +0800 Message-Id: <1444369526-2227-7-git-send-email-famz@redhat.com> In-Reply-To: <1444369526-2227-1-git-send-email-famz@redhat.com> References: <1444369526-2227-1-git-send-email-famz@redhat.com> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.27 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x X-Received-From: 209.132.183.28 Cc: Kevin Wolf , Paolo Bonzini , qemu-block@nongnu.org, Stefan Hajnoczi Subject: [Qemu-devel] [PATCH 06/12] block: Introduce "drained begin/end" API X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.6.x The semantics is that after bdrv_drained_begin(bs), bs will not get new external requests until the matching bdrv_drained_end(bs). Signed-off-by: Fam Zheng --- block.c | 2 ++ block/io.c | 18 ++++++++++++++++++ include/block/block.h | 19 +++++++++++++++++++ include/block/block_int.h | 2 ++ 4 files changed, 41 insertions(+) diff --git a/block.c b/block.c index 1f90b47..9b28a07 100644 --- a/block.c +++ b/block.c @@ -2058,6 +2058,8 @@ static void bdrv_move_feature_fields(BlockDriverState *bs_dest, bs_dest->device_list = bs_src->device_list; bs_dest->blk = bs_src->blk; + bs_dest->quiesce_counter = bs_src->quiesce_counter; + memcpy(bs_dest->op_blockers, bs_src->op_blockers, sizeof(bs_dest->op_blockers)); } diff --git a/block/io.c b/block/io.c index 94e18e6..b0dde7f 100644 --- a/block/io.c +++ b/block/io.c @@ -2618,3 +2618,21 @@ void bdrv_flush_io_queue(BlockDriverState *bs) } bdrv_start_throttled_reqs(bs); } + +void bdrv_drained_begin(BlockDriverState *bs) +{ + if (bs->quiesce_counter++) { + return; + } + aio_disable_clients(bdrv_get_aio_context(bs), AIO_CLIENT_EXTERNAL); + bdrv_drain(bs); +} + +void bdrv_drained_end(BlockDriverState *bs) +{ + assert(bs->quiesce_counter > 0); + if (--bs->quiesce_counter > 0) { + return; + } + aio_enable_clients(bdrv_get_aio_context(bs), AIO_CLIENT_EXTERNAL); +} diff --git a/include/block/block.h b/include/block/block.h index 2dd6630..c4f6eef 100644 --- a/include/block/block.h +++ b/include/block/block.h @@ -619,4 +619,23 @@ void bdrv_flush_io_queue(BlockDriverState *bs); BlockAcctStats *bdrv_get_stats(BlockDriverState *bs); +/** + * bdrv_drained_begin: + * + * Begin a quiesced section for exclusive access to the BDS, by disabling + * external request sources including NBD server and device model. Note that + * this doesn't block timers or coroutines from submitting more requests, which + * means block_job_pause is still necessary. + * + * This function can be recursive. + */ +void bdrv_drained_begin(BlockDriverState *bs); + +/** + * bdrv_drained_end: + * + * End a quiescent section started by bdrv_drained_begin(). + */ +void bdrv_drained_end(BlockDriverState *bs); + #endif diff --git a/include/block/block_int.h b/include/block/block_int.h index 14ad4c3..7c58221 100644 --- a/include/block/block_int.h +++ b/include/block/block_int.h @@ -456,6 +456,8 @@ struct BlockDriverState { /* threshold limit for writes, in bytes. "High water mark". */ uint64_t write_threshold_offset; NotifierWithReturn write_threshold_notifier; + + int quiesce_counter; };