Since the commit 25b5ff1a86 ("qga: add mountpoint usage info to
GuestFilesystemInfo") we have 2 values reported in guest-get-fsinfo:
used = (f_blocks - f_bfree), total = (f_blocks - f_bfree + f_bavail).
These calculations might be obscure for the end user and require one to
actually get into QGA source to understand how they're obtained. Let's
just report the values f_blocks, f_bfree, f_bavail (in bytes) from
statvfs() as they are, letting the user decide how to process them further.

Originally-by: Yuri Pudgorodskiy <yur@virtuozzo.com>
Signed-off-by: Andrey Drobyshev <andrey.drobyshev@virtuozzo.com>
---
 qga/commands-posix.c | 16 +++++++---------
 qga/qapi-schema.json | 11 +++++++----
 2 files changed, 14 insertions(+), 13 deletions(-)

diff --git a/qga/commands-posix.c b/qga/commands-posix.c
index 26008db497..752ef509d0 100644
--- a/qga/commands-posix.c
+++ b/qga/commands-posix.c
@@ -1554,8 +1554,7 @@ static GuestFilesystemInfo *build_guest_fsinfo(struct FsMount *mount,
                                                Error **errp)
 {
     GuestFilesystemInfo *fs = g_malloc0(sizeof(*fs));
-    struct statvfs buf;
-    unsigned long used, nonroot_total, fr_size;
+    struct statvfs st;
     char *devpath = g_strdup_printf("/sys/dev/block/%u:%u",
                                     mount->devmajor, mount->devminor);
 
@@ -1563,15 +1562,14 @@ 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) == 0) {
-        fr_size = buf.f_frsize;
-        used = buf.f_blocks - buf.f_bfree;
-        nonroot_total = used + buf.f_bavail;
-        fs->used_bytes = used * fr_size;
-        fs->total_bytes = nonroot_total * fr_size;
+    if (statvfs(fs->mountpoint, &st) == 0) {
+        fs->total_bytes = st.f_blocks * st.f_frsize;
+        fs->free_bytes = st.f_bfree * st.f_frsize;
+        fs->avail_bytes = st.f_bavail * st.f_frsize;
 
         fs->has_total_bytes = true;
-        fs->has_used_bytes = true;
+        fs->has_free_bytes = true;
+        fs->has_avail_bytes = true;
     }
 
     g_free(devpath);
diff --git a/qga/qapi-schema.json b/qga/qapi-schema.json
index b8efe31897..1cce3c1df5 100644
--- a/qga/qapi-schema.json
+++ b/qga/qapi-schema.json
@@ -1030,9 +1030,12 @@
 #
 # @type: file system type string
 #
-# @used-bytes: file system used bytes (since 3.0)
+# @total-bytes: total file system size in bytes (since 8.3)
 #
-# @total-bytes: non-root file system total bytes (since 3.0)
+# @free-bytes: amount of free space in file system in bytes (since 8.3)
+#
+# @avail-bytes: amount of free space in file system for unprivileged
+#     users in bytes (since 8.3)
 #
 # @disk: an array of disk hardware information that the volume lies
 #     on, which may be empty if the disk type is not supported
@@ -1041,8 +1044,8 @@
 ##
 { 'struct': 'GuestFilesystemInfo',
   'data': {'name': 'str', 'mountpoint': 'str', 'type': 'str',
-           '*used-bytes': 'uint64', '*total-bytes': 'uint64',
-           'disk': ['GuestDiskAddress']} }
+           '*total-bytes': 'uint64', '*free-bytes': 'uint64',
+           '*avail-bytes': 'uint64', 'disk': ['GuestDiskAddress']} }
 
 ##
 # @guest-get-fsinfo:
-- 
2.39.3

Best Regards,
Konstantin Kostiuk.


On Mon, Feb 26, 2024 at 7:02 PM Andrey Drobyshev <
andrey.drobyshev@virtuozzo.com> wrote:

> Since the commit 25b5ff1a86 ("qga: add mountpoint usage info to
> GuestFilesystemInfo") we have 2 values reported in guest-get-fsinfo:
> used = (f_blocks - f_bfree), total = (f_blocks - f_bfree + f_bavail).
> These calculations might be obscure for the end user and require one to
> actually get into QGA source to understand how they're obtained. Let's
> just report the values f_blocks, f_bfree, f_bavail (in bytes) from
> statvfs() as they are, letting the user decide how to process them further.
>
> Originally-by: Yuri Pudgorodskiy <yur@virtuozzo.com>
> Signed-off-by: Andrey Drobyshev <andrey.drobyshev@virtuozzo.com>
> ---
>  qga/commands-posix.c | 16 +++++++---------
>  qga/qapi-schema.json | 11 +++++++----
>  2 files changed, 14 insertions(+), 13 deletions(-)
>
> diff --git a/qga/commands-posix.c b/qga/commands-posix.c
> index 26008db497..752ef509d0 100644
> --- a/qga/commands-posix.c
> +++ b/qga/commands-posix.c
> @@ -1554,8 +1554,7 @@ static GuestFilesystemInfo
> *build_guest_fsinfo(struct FsMount *mount,
>                                                 Error **errp)
>  {
>      GuestFilesystemInfo *fs = g_malloc0(sizeof(*fs));
> -    struct statvfs buf;
> -    unsigned long used, nonroot_total, fr_size;
> +    struct statvfs st;
>      char *devpath = g_strdup_printf("/sys/dev/block/%u:%u",
>                                      mount->devmajor, mount->devminor);
>
> @@ -1563,15 +1562,14 @@ 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) == 0) {
> -        fr_size = buf.f_frsize;
> -        used = buf.f_blocks - buf.f_bfree;
> -        nonroot_total = used + buf.f_bavail;
> -        fs->used_bytes = used * fr_size;
> -        fs->total_bytes = nonroot_total * fr_size;
> +    if (statvfs(fs->mountpoint, &st) == 0) {
> +        fs->total_bytes = st.f_blocks * st.f_frsize;
> +        fs->free_bytes = st.f_bfree * st.f_frsize;
> +        fs->avail_bytes = st.f_bavail * st.f_frsize;
>
>          fs->has_total_bytes = true;
> -        fs->has_used_bytes = true;
> +        fs->has_free_bytes = true;
> +        fs->has_avail_bytes = true;
>      }
>
>      g_free(devpath);
> diff --git a/qga/qapi-schema.json b/qga/qapi-schema.json
> index b8efe31897..1cce3c1df5 100644
> --- a/qga/qapi-schema.json
> +++ b/qga/qapi-schema.json
> @@ -1030,9 +1030,12 @@
>  #
>  # @type: file system type string
>  #
> -# @used-bytes: file system used bytes (since 3.0)
> +# @total-bytes: total file system size in bytes (since 8.3)
>  #
> -# @total-bytes: non-root file system total bytes (since 3.0)
> +# @free-bytes: amount of free space in file system in bytes (since 8.3)
>

I don't agree with this as it breaks backward compatibility. If we want to
get
these changes we should release a new version with both old and new fields
and mark old as deprecated to get a time for everyone who uses this
API updates its solutions.

A similar thing was with replacing the 'blacklist' command line.
https://gitlab.com/qemu-project/qemu/-/commit/582a098e6ca00dd42f317dad8affd13e5a20bc42
Currently, we support both 'blacklist' and 'block-rpcs' command line options
but the first one wrote a warning.

@Marc-André Lureau <marcandre.lureau@redhat.com> @Philippe Mathieu-Daudé
<philmd@linaro.org>
What do you think about this?


> +#
> +# @avail-bytes: amount of free space in file system for unprivileged
> +#     users in bytes (since 8.3)
>  #
>  # @disk: an array of disk hardware information that the volume lies
>  #     on, which may be empty if the disk type is not supported
> @@ -1041,8 +1044,8 @@
>  ##
>  { 'struct': 'GuestFilesystemInfo',
>    'data': {'name': 'str', 'mountpoint': 'str', 'type': 'str',
> -           '*used-bytes': 'uint64', '*total-bytes': 'uint64',
> -           'disk': ['GuestDiskAddress']} }
> +           '*total-bytes': 'uint64', '*free-bytes': 'uint64',
> +           '*avail-bytes': 'uint64', 'disk': ['GuestDiskAddress']} }
>
>  ##
>  # @guest-get-fsinfo:
> --
> 2.39.3
>
>
>

On 2/26/24 20:50, Konstantin Kostiuk wrote:
> 
> Best Regards,
> Konstantin Kostiuk.
> 
> 
> On Mon, Feb 26, 2024 at 7:02 PM Andrey Drobyshev
> <andrey.drobyshev@virtuozzo.com <mailto:andrey.drobyshev@virtuozzo.com>>
> wrote:
> 
>     Since the commit 25b5ff1a86 ("qga: add mountpoint usage info to
>     GuestFilesystemInfo") we have 2 values reported in guest-get-fsinfo:
>     used = (f_blocks - f_bfree), total = (f_blocks - f_bfree + f_bavail).
>     These calculations might be obscure for the end user and require one to
>     actually get into QGA source to understand how they're obtained. Let's
>     just report the values f_blocks, f_bfree, f_bavail (in bytes) from
>     statvfs() as they are, letting the user decide how to process them
>     further.
> 
>     Originally-by: Yuri Pudgorodskiy <yur@virtuozzo.com
>     <mailto:yur@virtuozzo.com>>
>     Signed-off-by: Andrey Drobyshev <andrey.drobyshev@virtuozzo.com
>     <mailto:andrey.drobyshev@virtuozzo.com>>
>     ---
>      qga/commands-posix.c | 16 +++++++---------
>      qga/qapi-schema.json | 11 +++++++----
>      2 files changed, 14 insertions(+), 13 deletions(-)
> 
>     diff --git a/qga/commands-posix.c b/qga/commands-posix.c
>     index 26008db497..752ef509d0 100644
>     --- a/qga/commands-posix.c
>     +++ b/qga/commands-posix.c
>     @@ -1554,8 +1554,7 @@ static GuestFilesystemInfo
>     *build_guest_fsinfo(strua5a0239ce5ct FsMount *mount,
>                                                     Error **errp)
>      {
>          GuestFilesystemInfo *fs = g_malloc0(sizeof(*fs));
>     -    struct statvfs buf;
>     -    unsigned long used, nonroot_total, fr_size;
>     +    struct statvfs st;
>          char *devpath = g_strdup_printf("/sys/dev/block/%u:%u",
>                                          mount->devmajor, mount->devminor);
> 
>     @@ -1563,15 +1562,14 @@ 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) == 0) {
>     -        fr_size = buf.f_frsize;
>     -        used = buf.f_blocks - buf.f_bfree;
>     -        nonroot_total = used + buf.f_bavail;
>     -        fs->used_bytes = used * fr_size;
>     -        fs->total_bytes = nonroot_total * fr_size;
>     +    if (statvfs(fs->mountpoint, &st) == 0) {
>     +        fs->total_bytes = st.f_blocks * st.f_frsize;
>     +        fs->free_bytes = st.f_bfree * st.f_frsize;
>     +        fs->avail_bytes = st.f_bavail * st.f_frsize;
> 
>              fs->has_total_bytes = true;
>     -        fs->has_used_bytes = true;
>     +        fs->has_free_bytes = true;
>     +        fs->has_avail_bytes = true;
>          }
> 
>          g_free(devpath);
>     diff --git a/qga/qapi-schema.json b/qga/qapi-schema.json
>     index b8efe31897..1cce3c1df5 100644
>     --- a/qga/qapi-schema.json
>     +++ b/qga/qapi-schema.json
>     @@ -1030,9 +1030,12 @@
>      #
>      # @type: file system type string
>      #
>     -# @used-bytes: file system used bytes (since 3.0)
>     +# @total-bytes: total file system size in bytes (since 8.3)
>      #
>     -# @total-bytes: non-root file system total bytes (since 3.0)
>     +# @free-bytes: amount of free space in file system in bytes (since 8.3)
> 
> 
> I don't agree with this as it breaks backward compatibility. If we want
> to get
> these changes we should release a new version with both old and new fields
> and mark old as deprecated to get a time for everyone who uses this
> API updates its solutions.
> 
> A similar thing was with replacing the 'blacklist' command line.
> https://gitlab.com/qemu-project/qemu/-/commit/582a098e6ca00dd42f317dad8affd13e5a20bc42 <https://gitlab.com/qemu-project/qemu/-/commit/582a098e6ca00dd42f317dad8affd13e5a20bc42>
> Currently, we support both 'blacklist' and 'block-rpcs' command line options
> but the first one wrote a warning.
>

I agree that marking the old values as deprecated does make sense.
Although my original intent with this patch is to make more sense of the
existing names (e.g. total-bytes to indicate true fs size instead of
just non-root fs).  If so, we'd eventually have to replace the original
total-bytes value with the one having new semantics.  Or we could rename
the existing value to smth like "total-bytes-nonroot".  But either way
breaks backward compatibility after all.  How would you suggest to
resolve it?

Andrey

> @Marc-André Lureau <mailto:marcandre.lureau@redhat.com> @Philippe
> Mathieu-Daudé <mailto:philmd@linaro.org> 
> What do you think about this?
>  
> [...]

Hi

On Tue, Feb 27, 2024 at 4:38 PM Andrey Drobyshev
<andrey.drobyshev@virtuozzo.com> wrote:
>
>
>
> On 2/26/24 20:50, Konstantin Kostiuk wrote:
> >
> > Best Regards,
> > Konstantin Kostiuk.
> >
> >
> > On Mon, Feb 26, 2024 at 7:02 PM Andrey Drobyshev
> > <andrey.drobyshev@virtuozzo.com <mailto:andrey.drobyshev@virtuozzo.com>>
> > wrote:
> >
> >     Since the commit 25b5ff1a86 ("qga: add mountpoint usage info to
> >     GuestFilesystemInfo") we have 2 values reported in guest-get-fsinfo:
> >     used = (f_blocks - f_bfree), total = (f_blocks - f_bfree + f_bavail).
> >     These calculations might be obscure for the end user and require one to
> >     actually get into QGA source to understand how they're obtained. Let's
> >     just report the values f_blocks, f_bfree, f_bavail (in bytes) from
> >     statvfs() as they are, letting the user decide how to process them
> >     further.
> >
> >     Originally-by: Yuri Pudgorodskiy <yur@virtuozzo.com
> >     <mailto:yur@virtuozzo.com>>
> >     Signed-off-by: Andrey Drobyshev <andrey.drobyshev@virtuozzo.com
> >     <mailto:andrey.drobyshev@virtuozzo.com>>
> >     ---
> >      qga/commands-posix.c | 16 +++++++---------
> >      qga/qapi-schema.json | 11 +++++++----
> >      2 files changed, 14 insertions(+), 13 deletions(-)
> >
> >     diff --git a/qga/commands-posix.c b/qga/commands-posix.c
> >     index 26008db497..752ef509d0 100644
> >     --- a/qga/commands-posix.c
> >     +++ b/qga/commands-posix.c
> >     @@ -1554,8 +1554,7 @@ static GuestFilesystemInfo
> >     *build_guest_fsinfo(strua5a0239ce5ct FsMount *mount,
> >                                                     Error **errp)
> >      {
> >          GuestFilesystemInfo *fs = g_malloc0(sizeof(*fs));
> >     -    struct statvfs buf;
> >     -    unsigned long used, nonroot_total, fr_size;
> >     +    struct statvfs st;
> >          char *devpath = g_strdup_printf("/sys/dev/block/%u:%u",
> >                                          mount->devmajor, mount->devminor);
> >
> >     @@ -1563,15 +1562,14 @@ 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) == 0) {
> >     -        fr_size = buf.f_frsize;
> >     -        used = buf.f_blocks - buf.f_bfree;
> >     -        nonroot_total = used + buf.f_bavail;
> >     -        fs->used_bytes = used * fr_size;
> >     -        fs->total_bytes = nonroot_total * fr_size;
> >     +    if (statvfs(fs->mountpoint, &st) == 0) {
> >     +        fs->total_bytes = st.f_blocks * st.f_frsize;
> >     +        fs->free_bytes = st.f_bfree * st.f_frsize;
> >     +        fs->avail_bytes = st.f_bavail * st.f_frsize;
> >
> >              fs->has_total_bytes = true;
> >     -        fs->has_used_bytes = true;
> >     +        fs->has_free_bytes = true;
> >     +        fs->has_avail_bytes = true;
> >          }
> >
> >          g_free(devpath);
> >     diff --git a/qga/qapi-schema.json b/qga/qapi-schema.json
> >     index b8efe31897..1cce3c1df5 100644
> >     --- a/qga/qapi-schema.json
> >     +++ b/qga/qapi-schema.json
> >     @@ -1030,9 +1030,12 @@
> >      #
> >      # @type: file system type string
> >      #
> >     -# @used-bytes: file system used bytes (since 3.0)
> >     +# @total-bytes: total file system size in bytes (since 8.3)
> >      #
> >     -# @total-bytes: non-root file system total bytes (since 3.0)
> >     +# @free-bytes: amount of free space in file system in bytes (since 8.3)
> >
> >
> > I don't agree with this as it breaks backward compatibility. If we want
> > to get
> > these changes we should release a new version with both old and new fields
> > and mark old as deprecated to get a time for everyone who uses this
> > API updates its solutions.
> >
> > A similar thing was with replacing the 'blacklist' command line.
> > https://gitlab.com/qemu-project/qemu/-/commit/582a098e6ca00dd42f317dad8affd13e5a20bc42 <https://gitlab.com/qemu-project/qemu/-/commit/582a098e6ca00dd42f317dad8affd13e5a20bc42>
> > Currently, we support both 'blacklist' and 'block-rpcs' command line options
> > but the first one wrote a warning.
> >
>
> I agree that marking the old values as deprecated does make sense.
> Although my original intent with this patch is to make more sense of the
> existing names (e.g. total-bytes to indicate true fs size instead of
> just non-root fs).  If so, we'd eventually have to replace the original
> total-bytes value with the one having new semantics.  Or we could rename
> the existing value to smth like "total-bytes-nonroot".  But either way
> breaks backward compatibility after all.  How would you suggest to
> resolve it?


Why break backward compatibility? Don't break other systems (win32)
when you propose a patch.

QGA API aims to be cross-platform. Any system should be able to report
some kind of meaningful used and total disk space. I don't see much
reason to change that.

If we need Posix-specific values reported by statvfs(), we can have
extra optional struct/fields.

Fwiw, I find it more obscure to report statvfs values :) Perhaps we
should simply document better where those values are coming from,
instead of reporting more system-specific details.

On 2/28/24 09:55, Marc-André Lureau wrote:
> [Вы нечасто получаете письма от marcandre.lureau@redhat.com. Узнайте, почему это важно, по адресу https://aka.ms/LearnAboutSenderIdentification ]
> 
> Hi
> 
> On Tue, Feb 27, 2024 at 4:38 PM Andrey Drobyshev
> <andrey.drobyshev@virtuozzo.com> wrote:
>>
>>
>>
>> On 2/26/24 20:50, Konstantin Kostiuk wrote:
>>>
>>> Best Regards,
>>> Konstantin Kostiuk.
>>>
>>>
>>> On Mon, Feb 26, 2024 at 7:02 PM Andrey Drobyshev
>>> <andrey.drobyshev@virtuozzo.com <mailto:andrey.drobyshev@virtuozzo.com>>
>>> wrote:
>>>
>>>     Since the commit 25b5ff1a86 ("qga: add mountpoint usage info to
>>>     GuestFilesystemInfo") we have 2 values reported in guest-get-fsinfo:
>>>     used = (f_blocks - f_bfree), total = (f_blocks - f_bfree + f_bavail).
>>>     These calculations might be obscure for the end user and require one to
>>>     actually get into QGA source to understand how they're obtained. Let's
>>>     just report the values f_blocks, f_bfree, f_bavail (in bytes) from
>>>     statvfs() as they are, letting the user decide how to process them
>>>     further.
>>>
>>>     Originally-by: Yuri Pudgorodskiy <yur@virtuozzo.com
>>>     <mailto:yur@virtuozzo.com>>
>>>     Signed-off-by: Andrey Drobyshev <andrey.drobyshev@virtuozzo.com
>>>     <mailto:andrey.drobyshev@virtuozzo.com>>
>>>     ---
>>>      qga/commands-posix.c | 16 +++++++---------
>>>      qga/qapi-schema.json | 11 +++++++----
>>>      2 files changed, 14 insertions(+), 13 deletions(-)
>>>
>>>     diff --git a/qga/commands-posix.c b/qga/commands-posix.c
>>>     index 26008db497..752ef509d0 100644
>>>     --- a/qga/commands-posix.c
>>>     +++ b/qga/commands-posix.c
>>>     @@ -1554,8 +1554,7 @@ static GuestFilesystemInfo
>>>     *build_guest_fsinfo(strua5a0239ce5ct FsMount *mount,
>>>                                                     Error **errp)
>>>      {
>>>          GuestFilesystemInfo *fs = g_malloc0(sizeof(*fs));
>>>     -    struct statvfs buf;
>>>     -    unsigned long used, nonroot_total, fr_size;
>>>     +    struct statvfs st;
>>>          char *devpath = g_strdup_printf("/sys/dev/block/%u:%u",
>>>                                          mount->devmajor, mount->devminor);
>>>
>>>     @@ -1563,15 +1562,14 @@ 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) == 0) {
>>>     -        fr_size = buf.f_frsize;
>>>     -        used = buf.f_blocks - buf.f_bfree;
>>>     -        nonroot_total = used + buf.f_bavail;
>>>     -        fs->used_bytes = used * fr_size;
>>>     -        fs->total_bytes = nonroot_total * fr_size;
>>>     +    if (statvfs(fs->mountpoint, &st) == 0) {
>>>     +        fs->total_bytes = st.f_blocks * st.f_frsize;
>>>     +        fs->free_bytes = st.f_bfree * st.f_frsize;
>>>     +        fs->avail_bytes = st.f_bavail * st.f_frsize;
>>>
>>>              fs->has_total_bytes = true;
>>>     -        fs->has_used_bytes = true;
>>>     +        fs->has_free_bytes = true;
>>>     +        fs->has_avail_bytes = true;
>>>          }
>>>
>>>          g_free(devpath);
>>>     diff --git a/qga/qapi-schema.json b/qga/qapi-schema.json
>>>     index b8efe31897..1cce3c1df5 100644
>>>     --- a/qga/qapi-schema.json
>>>     +++ b/qga/qapi-schema.json
>>>     @@ -1030,9 +1030,12 @@
>>>      #
>>>      # @type: file system type string
>>>      #
>>>     -# @used-bytes: file system used bytes (since 3.0)
>>>     +# @total-bytes: total file system size in bytes (since 8.3)
>>>      #
>>>     -# @total-bytes: non-root file system total bytes (since 3.0)
>>>     +# @free-bytes: amount of free space in file system in bytes (since 8.3)
>>>
>>>
>>> I don't agree with this as it breaks backward compatibility. If we want
>>> to get
>>> these changes we should release a new version with both old and new fields
>>> and mark old as deprecated to get a time for everyone who uses this
>>> API updates its solutions.
>>>
>>> A similar thing was with replacing the 'blacklist' command line.
>>> https://gitlab.com/qemu-project/qemu/-/commit/582a098e6ca00dd42f317dad8affd13e5a20bc42 <https://gitlab.com/qemu-project/qemu/-/commit/582a098e6ca00dd42f317dad8affd13e5a20bc42>
>>> Currently, we support both 'blacklist' and 'block-rpcs' command line options
>>> but the first one wrote a warning.
>>>
>>
>> I agree that marking the old values as deprecated does make sense.
>> Although my original intent with this patch is to make more sense of the
>> existing names (e.g. total-bytes to indicate true fs size instead of
>> just non-root fs).  If so, we'd eventually have to replace the original
>> total-bytes value with the one having new semantics.  Or we could rename
>> the existing value to smth like "total-bytes-nonroot".  But either way
>> breaks backward compatibility after all.  How would you suggest to
>> resolve it?
> 
> 
> Why break backward compatibility? Don't break other systems (win32)
> when you propose a patch.
> 
> QGA API aims to be cross-platform. Any system should be able to report
> some kind of meaningful used and total disk space. I don't see much
> reason to change that.
> 
> If we need Posix-specific values reported by statvfs(), we can have
> extra optional struct/fields.
> 
> Fwiw, I find it more obscure to report statvfs values :) Perhaps we
> should simply document better where those values are coming from,
> instead of reporting more system-specific details.
> 

Agreed, keeping API compatible with Win version is a valid point.  I've
checked Win32 API page for GetDiskFreeSpaceExA(), and it seems
TotalNumberOfBytes they return is exactly for the non-privileged user.
So that's probably the root for such a design:
https://learn.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-getdiskfreespaceexa

Let me add an extra optional field then which we'd only fill on POSIX.
We might call it 'total-bytes-root' to highlight the difference.  I'd
also follow your advice and document where those values come from in
both POSIX and Win case.

I'll send this in v2.

Andrey