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Re: [PATCH v2 0/4] nbd/server: Quiesce coroutines on context switch
From: |
Eric Blake |
Subject: |
Re: [PATCH v2 0/4] nbd/server: Quiesce coroutines on context switch |
Date: |
Wed, 20 Jan 2021 14:49:14 -0600 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 |
On 12/14/20 11:05 AM, Sergio Lopez wrote:
> This series allows the NBD server to properly switch between AIO contexts,
> having quiesced recv_coroutine and send_coroutine before doing the transition.
>
> We need this because we send back devices running in IO Thread owned contexts
> to the main context when stopping the data plane, something that can happen
> multiple times during the lifetime of a VM (usually during the boot sequence
> or
> on a reboot), and we drag the NBD server of the correspoing export with it.
>
> While there, fix also a problem caused by a cross-dependency between
> closing the export's client connections and draining the block
> layer. The visible effect of this problem was QEMU getting hung when
> the guest request a power off while there's an active NBD client.
>
> v2:
> - Replace "virtio-blk: Acquire context while switching them on
> dataplane start" with "block: Honor blk_set_aio_context() context
> requirements" (Kevin Wolf)
> - Add "block: Avoid processing BDS twice in
> bdrv_set_aio_context_ignore()"
> - Add "block: Close block exports in two steps"
> - Rename nbd_read_eof() to nbd_server_read_eof() (Eric Blake)
> - Fix double space and typo in comment. (Eric Blake)
ping - where do we stand on this series? Patches 1 and 3 have positive
reviews, I'll queue them now; patches 2 and 4 had enough comments that
I'm guessing I should wait for a v3?
>
> Sergio Lopez (4):
> block: Honor blk_set_aio_context() context requirements
> block: Avoid processing BDS twice in bdrv_set_aio_context_ignore()
> nbd/server: Quiesce coroutines on context switch
> block: Close block exports in two steps
>
> block.c | 27 ++++++-
> block/export/export.c | 10 +--
> blockdev-nbd.c | 2 +-
> hw/block/dataplane/virtio-blk.c | 4 ++
> hw/block/dataplane/xen-block.c | 7 +-
> hw/scsi/virtio-scsi.c | 6 +-
> include/block/export.h | 4 +-
> nbd/server.c | 120 ++++++++++++++++++++++++++++----
> qemu-nbd.c | 2 +-
> stubs/blk-exp-close-all.c | 2 +-
> 10 files changed, 156 insertions(+), 28 deletions(-)
>
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3226
Virtualization: qemu.org | libvirt.org
- Re: [PATCH v2 0/4] nbd/server: Quiesce coroutines on context switch,
Eric Blake <=