[PATCH v2 02/11] qemu: Drop two layers of nesting of memoryBackingDir

[Daniel P. Berrangé]

On Thu, Mar 26, 2020 at 04:15:06PM +0100, Michal Privoznik wrote:
> Initially introduced in v3.10.0-rc1~172.
> 
> When generating a path for memory-backend-file or -mem-path, qemu
> driver will use the following pattern:
> 
>   $memoryBackingDir/libvirt/qemu/$id-$shortName
> 
> where $memoryBackingDir defaults to /var/lib/libvirt/qemu/ram but
> can be overridden in qemu.conf. Anyway, the "/libvirt/qemu/" part
> looks redundant, because it's already contained in the default,
> or creates unnecessary nesting if overridden in qemu.conf.

I think this was copied from our earlier huge pages code
which used /dev/hugepages, and then added "/libvirt/qemu"
to it.

Now we're stripping off "/libvirt/qemu" though, we're liable
to a filename clashes if someone edits qemu.conf to point to
/dev/shm.

IOW, even though "/libvirt/qemu" is redundant when using our
default path, I think we need to keep it to avoid clashing
with custom paths.


Regards,
Daniel
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