Re: [Qemu-devel] [PATCH v2] dump: Show custom message for ENOSPC

[Eric Blake <eblake@redhat.com>]

On 02/09/2018 02:26 PM, Yasmin Beatriz wrote:
> This patch intends to make a more specific message for when
> the system has not enough space to save guest memory.
> 
> Reported-by: yilzhang@redhat.com
> Cc: Jose Ricardo Ziviani <joserz@linux.vnet.ibm.com>
> Signed-off-by: Yasmin Beatriz <yasmins@linux.vnet.ibm.com>
> ---

> @@ -364,7 +364,11 @@ static void write_data(DumpState *s, void *buf, int length, Error **errp)
>   
>       ret = fd_write_vmcore(buf, length, s);
>       if (ret < 0) {
> -        error_setg(errp, "dump: failed to save memory");
> +        if (ret == -ENOSPC) {
> +            error_setg(errp, "dump: not enough space to save memory");
> +        } else {
> +            error_setg(errp, "dump: failed to save memory");
> +        }

Why is this caller the only one in the file that gets distinguished 
error messages?  And why not use error_setg_errno() instead of 
open-coding just one special errno value?  If you're changing the return 
value of fd_write_vmcore() anyways, I'd suggest that ALL callers in the 
file be updated to use error_setg_errno().

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org