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

[Pavel Hrdina]

On Wed, Aug 04, 2021 at 10:26:41AM +0200, Michal Prívozník wrote:
> On 8/4/21 10:22 AM, Pavel Hrdina wrote:
> > On Wed, Aug 04, 2021 at 10:06:17AM +0200, Michal Prívozník wrote:
> >> 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?
> > 
> > Good question :) I was lazy so I looked for first similar code in
> > libvirt codebase and copied it. You are right, stat should be enough
> > as according to man page stat and fstat are identical except or the
> > fd vs path parameter. I'll fix it before pushing or should I send a v2?
> 
> No need, just drop open() and switch to stat() before pushing. My
> Reviewed-by still applies.

OK, will do. Thanks for review!

Pavel
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