From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:38751) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZyD6m-0003rk-88 for qemu-devel@nongnu.org; Mon, 16 Nov 2015 01:17:45 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZyD6l-0008Bj-7F for qemu-devel@nongnu.org; Mon, 16 Nov 2015 01:17:44 -0500 Date: Mon, 16 Nov 2015 14:17:32 +0800 From: Fam Zheng Message-ID: <20151116061732.GC20672@ad.usersys.redhat.com> References: <1447345846-15624-1-git-send-email-pl@kamp.de> <564667C3.8010306@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <564667C3.8010306@redhat.com> Subject: Re: [Qemu-devel] [PATCH V4 0/6] ide: avoid main-loop hang on CDROM/NFS failure List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: John Snow Cc: kwolf@redhat.com, qemu-block@nongnu.org, jcody@redhat.com, Peter Lieven , qemu-devel@nongnu.org, Stefan Hajnoczi On Fri, 11/13 17:44, John Snow wrote: > > > On 11/12/2015 11:30 AM, Peter Lieven wrote: > > This series aims at avoiding a hanging main-loop if a vserver has a > > CDROM image mounted from a NFS share and that NFS share goes down. > > Typical situation is that users mount an CDROM ISO to install something > > and then forget to eject that CDROM afterwards. > > As a consequence this mounted CD is able to bring down the > > whole vserver if the backend NFS share is unreachable. This is bad > > especially if the CDROM itself is not needed anymore at this point. > > > > v3->v4: - Patch 1: remove buf argument for cd_read_sector{_sync} > > - Patch 1: fix iov_base offset for 2352 sector size > > - Patch 2: fix indent [Fam] > > - Patch 3: fix leaking of req->iov.iov_base [Fam] > > > > v2->v3: - adressed Stefans comments on Patch 1 > > - added patches 2,4,5,6 > > - avoided the term cancel in Patch 3. Added an iovec, > > added a BH [Stefan] > > v1->v2: - fix offset for 2352 byte sector size [Kevin] > > - use a sync request if we continue an elementary transfer. > > As John pointed out we enter a race condition between next > > IDE command and async transfer otherwise. This is sill not > > optimal, but it fixes the NFS down problems for all cases where > > the NFS server goes down while there is no PIO CD activity. > > Of course, it could still happen during a PIO transfer, but I > > expect this to be the unlikelier case. > > I spent some effort trying to read more sectors at once and > > avoiding continuation of elementary transfers, but with > > whatever I came up it was destroying migration between different > > Qemu versions. I have a quite hackish patch that works and > > should survive migration, but I am not happy with it. So I > > would like to start with this version as it is a big improvement > > already. > > - Dropped Patch 5 because it is upstream meanwhile. > > > > Peter Lieven (6): > > ide/atapi: make PIO read requests async > > block: add blk_abort_aio_request > > ide: add support for IDEBufferedRequest > > ide: orphan all buffered requests on DMA cancel > > ide: enable buffered requests for ATAPI devices > > ide: enable buffered requests for PIO read requests > > > > block/block-backend.c | 17 +++---- > > hw/ide/atapi.c | 103 +++++++++++++++++++++++++++++++++++------ > > hw/ide/core.c | 51 +++++++++++++++++++- > > hw/ide/internal.h | 14 ++++++ > > hw/ide/pci.c | 19 ++++++++ > > include/sysemu/block-backend.h | 3 ++ > > 6 files changed, 182 insertions(+), 25 deletions(-) > > > > It looks sane to me: > > Reviewed-by: John Snow > > Fam, Stefan: Do you think this is still sane for 2.5? I am inclined to > get it in as a fix, especially since we've been bouncing it around for > so long. I have no objection here, there is no new feature in the series, and guest hanging right after installing something is admittedly annoying to users. Thanks, Fam