From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:43765) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cqCJC-0002wp-F6 for qemu-devel@nongnu.org; Tue, 21 Mar 2017 01:26:15 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cqCJ7-0002Ia-JD for qemu-devel@nongnu.org; Tue, 21 Mar 2017 01:26:14 -0400 Received: from mx1.redhat.com ([209.132.183.28]:34302) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1cqCJ7-0002I9-Dt for qemu-devel@nongnu.org; Tue, 21 Mar 2017 01:26:09 -0400 Date: Tue, 21 Mar 2017 13:26:02 +0800 From: Fam Zheng Message-ID: <20170321052602.GA2785@lemon> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Subject: Re: [Qemu-devel] Assertion failure taking external snapshot with virtio drive + iothread List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Ed Swierk Cc: Kevin Wolf , Paolo Bonzini , qemu-devel@nongnu.org On Fri, 03/17 09:55, Ed Swierk wrote: > I'm running into the same problem taking an external snapshot with a > virtio-blk drive with iothread, so it's not specific to virtio-scsi. > Run a Linux guest on qemu master > > qemu-system-x86_64 -nographic -enable-kvm -monitor > telnet:0.0.0.0:1234,server,nowait -m 1024 -object > iothread,id=iothread1 -drive file=/x/drive.qcow2,if=none,id=drive0 > -device virtio-blk-pci,iothread=iothread1,drive=drive0 > > Then in the monitor > > snapshot_blkdev drive0 /x/snap1.qcow2 > > qemu bombs with > > qemu-system-x86_64: /x/qemu/include/block/aio.h:457: > aio_enable_external: Assertion `ctx->external_disable_cnt > 0' failed. > > whereas without the iothread the assertion failure does not occur. Can you test this one? --- diff --git a/blockdev.c b/blockdev.c index c5b2c2c..4c217d5 100644 --- a/blockdev.c +++ b/blockdev.c @@ -1772,6 +1772,8 @@ static void external_snapshot_prepare(BlkActionState *common, return; } + bdrv_set_aio_context(state->new_bs, state->aio_context); + /* This removes our old bs and adds the new bs. This is an operation that * can fail, so we need to do it in .prepare; undoing it for abort is * always possible. */ @@ -1789,8 +1791,6 @@ static void external_snapshot_commit(BlkActionState *common) ExternalSnapshotState *state = DO_UPCAST(ExternalSnapshotState, common, common); - bdrv_set_aio_context(state->new_bs, state->aio_context); - /* We don't need (or want) to use the transactional * bdrv_reopen_multiple() across all the entries at once, because we * don't want to abort all of them if one of them fails the reopen */