From mboxrd@z Thu Jan 1 00:00:00 1970 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 From: Fam Zheng 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> Subject: [Qemu-devel] [PATCH 06/12] block: Introduce "drained begin/end" API 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 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; }; -- 2.5.3