qga: add mountpoint usage info to GuestFilesystemInfo

This patch adds support for getting the usage of mounted
filesystem.
The usage of fs stored as used_bytes and total_bytes.
It's very useful when we try to monitor guest's filesystem.

Cc: Michael Roth <mdroth@linux.vnet.ibm.com>
Cc: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Chen Hanxiao <chenhanxiao@gmail.com>
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>

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 +1073,8 @@ 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;
     char *devpath = g_strdup_printf("/sys/dev/block/%u:%u",
                                     mount->devmajor, mount->devminor);
 
@@ -1079,7 +1082,19 @@ 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;
+
+        fs->has_total_bytes = true;
+        fs->has_used_bytes = true;
+    }
+
     g_free(devpath);
+
     return fs;
 }
 

qga/qapi-schema.json

@@ -848,6 +848,8 @@
 # @name: disk name
 # @mountpoint: mount point path
 # @type: file system type string
+# @used-bytes: file system used bytes (since 3.0)
+# @total-bytes: non-root file system total bytes (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
 #
@@ -855,6 +857,7 @@
 ##
 { 'struct': 'GuestFilesystemInfo',
   'data': {'name': 'str', 'mountpoint': 'str', 'type': 'str',
+           '*used-bytes': 'uint64', '*total-bytes': 'uint64',
            'disk': ['GuestDiskAddress']} }
 
 ##