From: Chen Hanxiao <chenhanxiao@gmail.com>

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 <mdroth@linux.vnet.ibm.com>
Signed-off-by: Chen Hanxiao <chenhanxiao@gmail.com>
---
v2:
   add description in qapi-schema and version numbers

 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..0d93c47a5d 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 u100, used, nonroot_total;
+    int 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)) {
+        error_setg_errno(errp, errno, "Failed to get statvfs");
+        return NULL;
+    }
+
+    used = buf.f_blocks - buf.f_bfree;
+    u100 = 100 * used;
+    nonroot_total = used + buf.f_bavail;
+    usage = u100 / nonroot_total + (u100 % nonroot_total != 0);
+
+    fs->usage = usage;
+
     g_free(devpath);
+
     return fs;
 }
 
diff --git a/qga/qapi-schema.json b/qga/qapi-schema.json
index 17884c7c70..98611b49af 100644
--- a/qga/qapi-schema.json
+++ b/qga/qapi-schema.json
@@ -846,13 +846,14 @@
 # @name: disk name
 # @mountpoint: mount point path
 # @type: file system type string
+# @usage: file system usage, integer between 0 and 100 (since 3.0)
 # @disk: an array of disk hardware information that the volume lies on,
 #        which may be empty if the disk type is not supported
 #
 # Since: 2.2
 ##
 { 'struct': 'GuestFilesystemInfo',
-  'data': {'name': 'str', 'mountpoint': 'str', 'type': 'str',
+  'data': {'name': 'str', 'mountpoint': 'str', 'type': 'str', 'usage': 'int',
            'disk': ['GuestDiskAddress']} }
 
 ##
-- 
2.17.0

On 05/30/2018 04:01 AM, Chen Hanxiao wrote:
> From: Chen Hanxiao <chenhanxiao@gmail.com>
> 
> 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 <mdroth@linux.vnet.ibm.com>
> Signed-off-by: Chen Hanxiao <chenhanxiao@gmail.com>
> ---
> v2:
>     add description in qapi-schema and version numbers

> +# @usage: file system usage, integer between 0 and 100 (since 3.0)

I still find this as being too imprecise.  Don't throw away data learned 
from the guest that the client might like to know.  Either provide a 
floating point between 0 and 1, or provide the two actual statvfs() 
numbers (used and total) directly and let the client perform the 
division to learn the ratio.

>   # @disk: an array of disk hardware information that the volume lies on,
>   #        which may be empty if the disk type is not supported
>   #
>   # Since: 2.2
>   ##
>   { 'struct': 'GuestFilesystemInfo',
> -  'data': {'name': 'str', 'mountpoint': 'str', 'type': 'str',
> +  'data': {'name': 'str', 'mountpoint': 'str', 'type': 'str', 'usage': 'int',
>              'disk': ['GuestDiskAddress']} }
>   
>   ##
> 

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