From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:34575) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XZNII-0002f0-EV for qemu-devel@nongnu.org; Wed, 01 Oct 2014 13:02:32 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XZNIB-0001gC-KL for qemu-devel@nongnu.org; Wed, 01 Oct 2014 13:02:26 -0400 Received: from mx1.redhat.com ([209.132.183.28]:39446) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XZNIB-0001fl-CF for qemu-devel@nongnu.org; Wed, 01 Oct 2014 13:02:19 -0400 Received: from int-mx11.intmail.prod.int.phx2.redhat.com (int-mx11.intmail.prod.int.phx2.redhat.com [10.5.11.24]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id s91H2IuB020983 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL) for ; Wed, 1 Oct 2014 13:02:18 -0400 From: Stefan Hajnoczi Date: Wed, 1 Oct 2014 18:01:54 +0100 Message-Id: <1412182919-9550-7-git-send-email-stefanha@redhat.com> In-Reply-To: <1412182919-9550-1-git-send-email-stefanha@redhat.com> References: <1412182919-9550-1-git-send-email-stefanha@redhat.com> Subject: [Qemu-devel] [PATCH 06/11] block: add bdrv_drain() List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Kevin Wolf , Paolo Bonzini , Fam Zheng , Stefan Hajnoczi , Max Reitz Now that op blockers are in use, we can ensure that no other sources are generating I/O on a BlockDriverState. Therefore it is possible to drain requests for a single BDS. Signed-off-by: Stefan Hajnoczi --- block.c | 36 +++++++++++++++++++++++++++++------- include/block/block.h | 1 + 2 files changed, 30 insertions(+), 7 deletions(-) diff --git a/block.c b/block.c index c5a251c..48305c4 100644 --- a/block.c +++ b/block.c @@ -1918,6 +1918,34 @@ static bool bdrv_requests_pending(BlockDriverState *bs) return false; } +static bool bdrv_drain_one(BlockDriverState *bs) +{ + bool bs_busy; + + bdrv_flush_io_queue(bs); + bdrv_start_throttled_reqs(bs); + bs_busy = bdrv_requests_pending(bs); + bs_busy |= aio_poll(bdrv_get_aio_context(bs), bs_busy); + return bs_busy; +} + +/* + * Wait for pending requests to complete on a single BlockDriverState subtree + * + * See the warning in bdrv_drain_all(). This function can only be called if + * you are sure nothing can generate I/O because you have op blockers + * installed. + * + * Note that unlike bdrv_drain_all(), the caller must hold the BlockDriverState + * AioContext. + */ +void bdrv_drain(BlockDriverState *bs) +{ + while (bdrv_drain_one(bs)) { + /* Keep iterating */ + } +} + /* * Wait for pending requests to complete across all BlockDriverStates * @@ -1941,16 +1969,10 @@ void bdrv_drain_all(void) QTAILQ_FOREACH(bs, &bdrv_states, device_list) { AioContext *aio_context = bdrv_get_aio_context(bs); - bool bs_busy; aio_context_acquire(aio_context); - bdrv_flush_io_queue(bs); - bdrv_start_throttled_reqs(bs); - bs_busy = bdrv_requests_pending(bs); - bs_busy |= aio_poll(aio_context, bs_busy); + busy |= bdrv_drain_one(bs); aio_context_release(aio_context); - - busy |= bs_busy; } } } diff --git a/include/block/block.h b/include/block/block.h index 3318f0d..61df804 100644 --- a/include/block/block.h +++ b/include/block/block.h @@ -372,6 +372,7 @@ int bdrv_flush(BlockDriverState *bs); int coroutine_fn bdrv_co_flush(BlockDriverState *bs); int bdrv_flush_all(void); void bdrv_close_all(void); +void bdrv_drain(BlockDriverState *bs); void bdrv_drain_all(void); int bdrv_discard(BlockDriverState *bs, int64_t sector_num, int nb_sectors); -- 1.9.3