Re: [Qemu-devel] [PATCH v4] qga: add mountpoint usage to GuestFilesystemInfo

[Chen Hanxiao]

At 2018-06-01 20:19:56, "Daniel P. Berrangé" <address@hidden> wrote:
>On Fri, Jun 01, 2018 at 02:11:21PM +0800, Chen Hanxiao wrote:
>> From: Chen Hanxiao <address@hidden>
>> 
>> This patch adds support for getting the usage of mounted
>> filesystem.
>> It's very useful when we try to monitor guest's filesystem.
>> 
>> Cc: Michael Roth <address@hidden>
>> Cc: Eric Blake <address@hidden>
>> Signed-off-by: Chen Hanxiao <address@hidden>
>> 
>> ---
>> v2:
>>    add description in qapi-schema and version numbers
>> v3:
>>    use float for usage to get more precision.
>> v4:
>>    make usage as a best-effort query and mark it as optional.
>> 
>>  qga/commands-posix.c | 17 +++++++++++++++++
>>  qga/qapi-schema.json |  3 ++-
>>  2 files changed, 19 insertions(+), 1 deletion(-)
>> 
>> diff --git a/qga/commands-posix.c b/qga/commands-posix.c
>> index 0dc219dbcf..4facc76953 100644
>> --- a/qga/commands-posix.c
>> +++ b/qga/commands-posix.c
>> @@ -46,6 +46,7 @@ extern char **environ;
>>  #include <arpa/inet.h>
>>  #include <sys/socket.h>
>>  #include <net/if.h>
>> +#include <sys/statvfs.h>
>>  
>>  #ifdef FIFREEZE
>>  #define CONFIG_FSFREEZE
>> @@ -1072,6 +1073,9 @@ static GuestFilesystemInfo *build_guest_fsinfo(struct 
>> FsMount *mount,
>>                                                 Error **errp)
>>  {
>>      GuestFilesystemInfo *fs = g_malloc0(sizeof(*fs));
>> +    struct statvfs buf;
>> +    unsigned long used, nonroot_total;
>> +    double usage;
>>      char *devpath = g_strdup_printf("/sys/dev/block/%u:%u",
>>                                      mount->devmajor, mount->devminor);
>>  
>> @@ -1079,7 +1083,20 @@ static GuestFilesystemInfo *build_guest_fsinfo(struct 
>> FsMount *mount,
>>      fs->type = g_strdup(mount->devtype);
>>      build_guest_fsinfo_for_device(devpath, fs, errp);
>>  
>> +    if (statvfs(fs->mountpoint, &buf)) {
>> +        fs->has_usage = false;
>> +        fs->usage = -1;
>> +    } else {
>> +        used = buf.f_blocks - buf.f_bfree;
>> +        nonroot_total = used + buf.f_bavail;
>> +        usage = (double) used / nonroot_total;
>
>Why calculate the usage here ?  IMHO it would make the command more useful
>if we just reported two separate "used_bytes" and "total_bytes" values. The
>app can convert to a percentage utilization value if they so desire, while
>other apps can now get the raw values

Thanks for your advice.
Will be fixed in v5.
Also adding support for qga-win.

Regards,
- Chen