Re: [Qemu-devel] [PATCH v5.1 2/2] qga-win: add driver path usage to GuestFilesystemInfo

[Eric Blake <eblake@redhat.com>]

On 06/01/2018 11:57 AM, Chen Hanxiao wrote:
> From: Chen Hanxiao <chenhanxiao@gmail.com>
> 
> This patch adds support for getting the usage of
> windows driver path.
> The usage of fs stored as used_bytes and total_bytes.
> 
> Cc: Michael Roth <mdroth@linux.vnet.ibm.com>
> Signed-off-by: Chen Hanxiao <chenhanxiao@gmail.com>
> ---
> v2:
>    unpack usage as used-bytes and total-bytes
> 

> @@ -699,10 +700,21 @@ static GuestFilesystemInfo *build_guest_fsinfo(char *guid, Error **errp)
>       fs_name[sizeof(fs_name) - 1] = 0;
>       fs = g_malloc(sizeof(*fs));
>       fs->name = g_strdup(guid);
> +    fs->has_total_bytes = false;
> +    fs->has_used_bytes = false;

Dead assignments.

>       if (len == 0) {
>           fs->mountpoint = g_strdup("System Reserved");
>       } else {
>           fs->mountpoint = g_strndup(mnt_point, len);
> +        if (GetDiskFreeSpaceEx(fs->mountpoint,
> +                               (PULARGE_INTEGER) & i64FreeBytesToCaller,
> +                               (PULARGE_INTEGER) & i64TotalBytes,
> +                               (PULARGE_INTEGER) & i64FreeBytes)) {
> +            fs->used_bytes = i64TotalBytes - i64FreeBytes;
> +            fs->total_bytes = i64TotalBytes;
> +            fs->has_total_bytes = true;
> +            fs->has_used_bytes = true;
> +        }

I'm less familiar with Windows API, so I won't give this R-b. But now 
that I read this patch, I do have a question: since both statvfs() and 
GetDiskFreeSpaceEx() give you free bytes rather than used bytes, and you 
had to perform a subtraction to report 'used-bytes' over QGA, would it 
make any more sense to instead report 'free-bytes' over QGA for less 
subtraction work on your end and so that the QGA interface is more 
similar to existing interfaces?

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