Re: [PATCH v2 0/3] block/nbd: fix crashers in reconnect while migrating

[Eric Blake <eblake@redhat.com>]

On 1/29/21 1:38 AM, Roman Kagan wrote:
> During the final phase of migration the NBD reconnection logic may
> encounter situations it doesn't expect during regular operation.
> 
> This series addresses some of them that make qemu crash.  They are
> reproducible when a vm with a secondary drive attached via nbd with
> non-zero "reconnect-delay" runs a stress load (fio with big queue depth)
> in the guest on that drive and is migrated (e.g. to a file), while the
> nbd server is SIGKILL-ed and restarted every second.
> 
> See the individual patches for specific crash conditions and more
> detailed explanations.
> 
> v1 -> v2:
> - fix corrupted backtraces in log messages
> - add r-b by Vladimir
> 

Thanks, queuing through my NBD tree.

> Roman Kagan (3):
>   block/nbd: only detach existing iochannel from aio_context
>   block/nbd: only enter connection coroutine if it's present
>   nbd: make nbd_read* return -EIO on error
> 
>  include/block/nbd.h |  7 ++++---
>  block/nbd.c         | 25 +++++++++++++++++--------
>  2 files changed, 21 insertions(+), 11 deletions(-)
> 

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org