From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:40319) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZkQVU-0000Cx-LH for qemu-devel@nongnu.org; Fri, 09 Oct 2015 01:46:20 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZkQVT-0003G8-NT for qemu-devel@nongnu.org; Fri, 09 Oct 2015 01:46:16 -0400 From: Fam Zheng Date: Fri, 9 Oct 2015 13:45:25 +0800 Message-Id: <1444369526-2227-12-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> Subject: [Qemu-devel] [PATCH 11/12] block: Introduce BlockDriver.bdrv_drain callback List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Kevin Wolf , Paolo Bonzini , qemu-block@nongnu.org, Stefan Hajnoczi Drivers can have internal request sources that generates IO, like the need_check_timer in QED. Since we want quiesced periods that contain nested event loops in block layer, we need to have a way to disable such event sources. Block drivers must implement the "bdrv_drain" callback if it has any internal sources that can generate I/O activity, like a timer or a worker thread (even in a library) that can schedule QEMUBH in an asynchronous callback. Signed-off-by: Fam Zheng --- block/io.c | 3 +++ include/block/block_int.h | 6 ++++++ 2 files changed, 9 insertions(+) diff --git a/block/io.c b/block/io.c index b0dde7f..ad4b456 100644 --- a/block/io.c +++ b/block/io.c @@ -247,6 +247,9 @@ void bdrv_drain(BlockDriverState *bs) { bool busy = true; + if (bs->drv && bs->drv->bdrv_drain) { + bs->drv->bdrv_drain(bs); + } while (busy) { /* Keep iterating */ bdrv_flush_io_queue(bs); diff --git a/include/block/block_int.h b/include/block/block_int.h index 7c58221..99359b2 100644 --- a/include/block/block_int.h +++ b/include/block/block_int.h @@ -288,6 +288,12 @@ struct BlockDriver { */ int (*bdrv_probe_geometry)(BlockDriverState *bs, HDGeometry *geo); + /** + * Drain and stop any internal sources of requests in the driver, and + * remain so until next I/O callback (e.g. bdrv_co_writev) is called. + */ + void (*bdrv_drain)(BlockDriverState *bs); + QLIST_ENTRY(BlockDriver) list; }; -- 2.5.3