Re: [libvirt] [PATCH v2 02/53] vircgroup: introduce virCgroupV2Available

On 10/05/2018 02:43 PM, Pavel Hrdina wrote: > We cannot detect only mount points to figure out whether cgroup v2 > is available because systemd uses cgroup v2 for process tracking and > all controllers are mounted as cgroup v1 controllers. > > To make sure that this is no the situation we need to check > 'cgroup.controllers' file if it's not empty to make sure that cgroup > v2 is not mounted only for process tracking. > > Signed-off-by: Pavel Hrdina <phrdina(a)redhat.com&gt; > --- > src/util/vircgroupv2.c | 59 ++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 59 insertions(+) > > diff --git a/src/util/vircgroupv2.c b/src/util/vircgroupv2.c > index 23bf81dae2..83944602d6 100644 > --- a/src/util/vircgroupv2.c > +++ b/src/util/vircgroupv2.c > @@ -19,6 +19,10 @@ > */ > #include <config.h> > > +#ifdef __linux__ > +# include <mntent.h> > +#endif /* __linux__ */ > + > #include "internal.h" > > #define __VIR_CGROUP_ALLOW_INCLUDE_PRIV_H__ > @@ -28,7 +32,9 @@ > #include "vircgroup.h" > #include "vircgroupbackend.h" > #include "vircgroupv2.h" > +#include "virfile.h" > #include "virlog.h" > +#include "virstring.h" > > VIR_LOG_INIT("util.cgroup"); > > @@ -41,8 +47,61 @@ VIR_ENUM_IMPL(virCgroupV2Controller, VIR_CGROUP_CONTROLLER_LAST, > > #ifdef __linux__ How about: static bool virCgroupV2Available(void) { bool ret = false; FILE *mounts = NULL; struct mntent entry; char buf[CGROUP_MAX_VAL]; if (!(mounts = fopen("/proc/mounts", "r"))) return false; while (getmntent_r(mounts, &entry, buf, sizeof(buf)) != NULL) { VIR_AUTOFREE(char *) contFile = NULL; VIR_AUTOFREE(char *) contStr = NULL; if (STRNEQ(entry.mnt_type, "cgroup2")) continue; /* Systemd uses cgroup v2 for process tracking but no controller is * available. We should consider this configuration as cgroup v2 is * not available. */ if (virAsprintf(&contFile, "%s/cgroup.controllers", entry.mnt_dir) < 0) goto cleanup; if (virFileReadAll(contFile, 1024 * 1024, &contStr) < 0) goto cleanup; if (STREQ(contStr, "")) continue; ret = true; break; } cleanup: VIR_FORCE_FCLOSE(mounts); return ret; }