Re: [PATCH v6 8/8] block/file: switch to use qemu_open/qemu_create for improved errors

[Richard Henderson]

On 9/3/20 8:22 AM, Daniel P. Berrangé wrote:
> Currently at startup if using cache=none on a filesystem lacking
> O_DIRECT such as tmpfs, at startup QEMU prints
> 
> qemu-system-x86_64: -drive file=/tmp/foo.img,cache=none: file system may not 
> support O_DIRECT
> qemu-system-x86_64: -drive file=/tmp/foo.img,cache=none: Could not open 
> '/tmp/foo.img': Invalid argument
> 
> while at QMP level the hint is missing, so QEMU reports just
> 
>   "error": {
>       "class": "GenericError",
>       "desc": "Could not open '/tmp/foo.img': Invalid argument"
>   }
> 
> which is close to useless for the end user trying to figure out what
> they did wrong.
> 
> With this change at startup QEMU prints
> 
> qemu-system-x86_64: -drive file=/tmp/foo.img,cache=none: Unable to open 
> '/tmp/foo.img': filesystem does not support O_DIRECT
> 
> while at the QMP level QEMU reports a massively more informative
> 
>   "error": {
>      "class": "GenericError",
>      "desc": "Unable to open '/tmp/foo.img': filesystem does not support 
> O_DIRECT"
>   }
> 
> Reviewed-by: Eric Blake <eblake@redhat.com>
> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> Reviewed-by: Markus Armbruster <armbru@redhat.com>
> Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
> ---

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

r~