On Nov 27, 2013, at 6:52 AM, Tigran Mkrtchyan <tigran.mkrtchyan@xxxxxxx> wrote:
> While working on a ganglia plugin for NFS I run into problem that
> /proc/self/mountstats is readable by process owner only. As ganglia
> changes collector threads effective uid, it can't access to mountstats
> file any more.
>
> The content of mountstats is equal for all processes and can be safely
> shared.
That is true only if there is a single mount namespace on your system. The content of mountstats depends on each process's mount namespace.
However, I see that mounts and mountinfo, which also depend on a process's mount namespace, are all S_IRUGO. I don't see a good reason mountstats should be different.
>
> Signed-off-by: Tigran Mkrtchyan <tigran.mkrtchyan@xxxxxxx>
> ---
> fs/proc/base.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/proc/base.c b/fs/proc/base.c
> index 03c8d74..d41e284 100644
> --- a/fs/proc/base.c
> +++ b/fs/proc/base.c
> @@ -2607,7 +2607,7 @@ static const struct pid_entry tgid_base_stuff[] = {
> LNK("exe", proc_exe_link),
> REG("mounts", S_IRUGO, proc_mounts_operations),
> REG("mountinfo", S_IRUGO, proc_mountinfo_operations),
> - REG("mountstats", S_IRUSR, proc_mountstats_operations),
> + REG("mountstats", S_IRUGO, proc_mountstats_operations),
> #ifdef CONFIG_PROC_PAGE_MONITOR
> REG("clear_refs", S_IWUSR, proc_clear_refs_operations),
> REG("smaps", S_IRUGO, proc_pid_smaps_operations),
> --
> 1.8.4.2
>
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--
Chuck Lever
chuck[dot]lever[at]oracle[dot]com
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