[libvirt PATCH 1/3] vircgroup: introduce virCgroupGetInode function

[Michal Prívozník]

On 8/3/21 4:29 PM, Pavel Hrdina wrote:
> For new feature Fibre Channel VMID we will need to get inode of the
> VM root cgroup as it is used in the new kernel API together with VMID.
> 
> Signed-off-by: Pavel Hrdina <phrdina at redhat.com>
> ---
>  src/libvirt_private.syms |  1 +
>  src/util/vircgroup.c     | 37 +++++++++++++++++++++++++++++++++++++
>  src/util/vircgroup.h     |  2 ++
>  3 files changed, 40 insertions(+)
> 
> diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
> index 6961cdb137..d8451fcfff 100644
> --- a/src/libvirt_private.syms
> +++ b/src/libvirt_private.syms
> @@ -1920,6 +1920,7 @@ virCgroupGetCpuShares;
>  virCgroupGetDevicePermsString;
>  virCgroupGetDomainTotalCpuStats;
>  virCgroupGetFreezerState;
> +virCgroupGetInode;
>  virCgroupGetMemoryHardLimit;
>  virCgroupGetMemorySoftLimit;
>  virCgroupGetMemoryStat;
> diff --git a/src/util/vircgroup.c b/src/util/vircgroup.c
> index 1b3b28342e..ea702e7b63 100644
> --- a/src/util/vircgroup.c
> +++ b/src/util/vircgroup.c
> @@ -3973,3 +3973,40 @@ virCgroupGetCpuPeriodQuota(virCgroup *cgroup, unsigned long long *period,
>  
>      return 0;
>  }
> +
> +
> +/**
> + * virCgroupGetInode:
> + *
> + * @cgroup: the cgroup to get inode for
> + *
> + * Get the @cgroup inode and return its value to the caller.
> + *
> + * Returns inode on success, -1 on error with error message reported.
> + */
> +int
> +virCgroupGetInode(virCgroup *cgroup)
> +{
> +    VIR_AUTOCLOSE fd = 0;
> +    struct stat st;
> +    int controller = virCgroupGetAnyController(cgroup);
> +    g_autofree char *path = NULL;
> +
> +    if (controller < 0)
> +        return -1;
> +
> +    if (virCgroupPathOfController(cgroup, controller, "", &path) < 0)
> +        return -1;
> +
> +    if ((fd = open(path, O_RDONLY | O_NONBLOCK)) < 0) {
> +        virReportSystemError(errno, _("failed to open cgroup '%s'"), path);
> +        return -1;
> +    }

Is the open() necessary? Why isn't plain stat() enough?

Michal