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Re: [Qemu-block] [Qemu-devel] [PATCH V4 0/6] ide: avoid main-loop hang o
From: |
John Snow |
Subject: |
Re: [Qemu-block] [Qemu-devel] [PATCH V4 0/6] ide: avoid main-loop hang on CDROM/NFS failure |
Date: |
Fri, 13 Nov 2015 12:18:15 -0500 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 |
On 11/13/2015 06:13 AM, Mark Cave-Ayland wrote:
> On 12/11/15 16:30, 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(-)
>
> Patches 4-6 look like they may handle issues I've found with migration
> in DMA requests on PPC g3beige and mac99 machines. Unfortunately due to
> alignment issues, the macio controller has implement its own versions of
> some of these routines, so should parts of these also be applied
> hw/ide/macio.c aswell?
>
>
> ATB,
>
> Mark.
>
I still might be suffering delusions that I can sneak this into 2.5 -- I
wouldn't mind reworking this to share with macio later if that's the case.
I don't think I'll make acceptance of this patchset conditional on macio
inclusion either way, though.
--js
- [Qemu-block] [PATCH V4 1/6] ide/atapi: make PIO read requests async, (continued)
- [Qemu-block] [PATCH V4 3/6] ide: add support for IDEBufferedRequest, Peter Lieven, 2015/11/12
- [Qemu-block] [PATCH V4 4/6] ide: orphan all buffered requests on DMA cancel, Peter Lieven, 2015/11/12
- [Qemu-block] [PATCH V4 2/6] block: add blk_abort_aio_request, Peter Lieven, 2015/11/12
- [Qemu-block] [PATCH V4 6/6] ide: enable buffered requests for PIO read requests, Peter Lieven, 2015/11/12
- [Qemu-block] [PATCH V4 5/6] ide: enable buffered requests for ATAPI devices, Peter Lieven, 2015/11/12
- Re: [Qemu-block] [Qemu-devel] [PATCH V4 0/6] ide: avoid main-loop hang on CDROM/NFS failure, Mark Cave-Ayland, 2015/11/13
- Re: [Qemu-block] [Qemu-devel] [PATCH V4 0/6] ide: avoid main-loop hang on CDROM/NFS failure,
John Snow <=
- Re: [Qemu-block] [Qemu-devel] [PATCH V4 0/6] ide: avoid main-loop hang on CDROM/NFS failure, John Snow, 2015/11/13