vircgroup: introduce virCgroupV2DetectControllers

Cgroup v2 has only single mount point for all controllers.  The list
of controllers is stored in cgroup.controllers file, name of controllers
are separated by space.

In cgroup v2 there is no cpuacct controller, the cpu.stat file always
exists with usage stats.

Signed-off-by: Pavel Hrdina <phrdina@redhat.com>

diff --git a/src/util/vircgroupv2.c b/src/util/vircgroupv2.c
index c1e7936457dab55dbae666598a357e2cf59e6c3c..77b644007869d8a9727949e34c0a7cd5208428d9 100644 (file)
--- a/src/util/vircgroupv2.c
+++ b/src/util/vircgroupv2.c
@@ -32,6 +32,7 @@
 #include "vircgroup.h"
 #include "vircgroupbackend.h"
 #include "vircgroupv2.h"
+#include "virerror.h"
 #include "virfile.h"
 #include "virlog.h"
 #include "virstring.h"
@@ -230,6 +231,73 @@ virCgroupV2StealPlacement(virCgroupPtr group)
 }
 
 
+static int
+virCgroupV2ParseControllersFile(virCgroupPtr group)
+{
+    int rc;
+    VIR_AUTOFREE(char *) contStr = NULL;
+    VIR_AUTOFREE(char *) contFile = NULL;
+    char **contList = NULL;
+    char **tmp;
+
+    if (virAsprintf(&contFile, "%s/cgroup.controllers",
+                    group->unified.mountPoint) < 0)
+        return -1;
+
+    rc = virFileReadAll(contFile, 1024 * 1024, &contStr);
+    if (rc < 0) {
+        virReportSystemError(errno, _("Unable to read from '%s'"), contFile);
+        return -1;
+    }
+
+    virTrimSpaces(contStr, NULL);
+
+    contList = virStringSplit(contStr, " ", 20);
+    if (!contList)
+        return -1;
+
+    tmp = contList;
+
+    while (*tmp) {
+        int type = virCgroupV2ControllerTypeFromString(*tmp);
+
+        if (type >= 0)
+            group->unified.controllers |= 1 << type;
+
+        tmp++;
+    }
+
+    virStringListFree(contList);
+
+    return 0;
+}
+
+
+static int
+virCgroupV2DetectControllers(virCgroupPtr group,
+                             int controllers)
+{
+    size_t i;
+
+    if (virCgroupV2ParseControllersFile(group) < 0)
+        return -1;
+
+    /* In cgroup v2 there is no cpuacct controller, the cpu.stat file always
+     * exists with usage stats. */
+    group->unified.controllers |= 1 << VIR_CGROUP_CONTROLLER_CPUACCT;
+
+    for (i = 0; i < VIR_CGROUP_CONTROLLER_LAST; i++)
+        VIR_DEBUG("Controller '%s' present=%s",
+                  virCgroupV2ControllerTypeToString(i),
+                  (group->unified.controllers & 1 << i) ? "yes" : "no");
+
+    if (controllers >= 0)
+        return controllers & group->unified.controllers;
+    else
+        return group->unified.controllers;
+}
+
+
 virCgroupBackend virCgroupV2Backend = {
     .type = VIR_CGROUP_BACKEND_TYPE_V2,
 
@@ -241,6 +309,7 @@ virCgroupBackend virCgroupV2Backend = {
     .detectPlacement = virCgroupV2DetectPlacement,
     .validatePlacement = virCgroupV2ValidatePlacement,
     .stealPlacement = virCgroupV2StealPlacement,
+    .detectControllers = virCgroupV2DetectControllers,
 };