Re: [Qemu-block] [Qemu-devel] [PATCH] file-posix: Consolidate the locking error message

[Fam Zheng]

On Fri, 06/01 13:43, Daniel P. Berrangé wrote:
> On Fri, Jun 01, 2018 at 05:18:35PM +0800, Fam Zheng wrote:
> > When hot-plugging a block device fails due to image locking errors,
> > users won't see the helpful 'Is another process using the image?'
> > message in QMP because currently the error hint is not carried over
> > there.
> > 
> > Even though extending QMP to include hint is a conceivably easy task,
> > Libvirt will need some change to consume that data.
> > 
> > Before that is fully sorted out, let's just do the easy fix by joining
> > the two lines.
> 
> There are many places in QEMU which uses error hints and these are all
> invisible to libvirt. Arbitrarily picking one hint to remove, while
> leaving everything else unfixed is not a very satisfactory approach.
> 
> If QEMU passes the hint in QMP, it is trivial for libvirt to be changed
> to append the hint when reporting its own error message, so can we just
> focus on fixing the root cause instead of special casing file-posix.c

The plan was to work on the QMP change in parallel, while this simple patch can
mitigate the confusion caused by the relatively vague message (the text itself
is going a bit on the cryptic side for people who don't know QEMU internals).

Fam