From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:50480) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZxN54-0000nt-38 for qemu-devel@nongnu.org; Fri, 13 Nov 2015 17:44:31 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZxN52-0003tg-0b for qemu-devel@nongnu.org; Fri, 13 Nov 2015 17:44:29 -0500 References: <1447345846-15624-1-git-send-email-pl@kamp.de> From: John Snow Message-ID: <564667C3.8010306@redhat.com> Date: Fri, 13 Nov 2015 17:44:19 -0500 MIME-Version: 1.0 In-Reply-To: <1447345846-15624-1-git-send-email-pl@kamp.de> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit 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: Peter Lieven Cc: kwolf@redhat.com, famz@redhat.com, qemu-block@nongnu.org, jcody@redhat.com, qemu-devel@nongnu.org, Stefan Hajnoczi 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. --js