Re: [RFC V2 PATCH] kernfs: create raw version kernfs_path_len and kernfs_path

[Shi, Yang]

On 2/27/2016 3:51 AM, Tejun Heo wrote:
> Hello,
>
> On Sat, Feb 27, 2016 at 6:45 AM, Thomas Gleixner <tglx@xxxxxxxxxxxxx> wrote:
> > > It can be, but we can print out the ino and userland can match that up
> > > with path if necessary.
> >
> > Wouldn't be cgroup id the better choice?
>
> AFAIK we aren't exposing cgroup id to userland anywhere right now.
> Eventually, I think the right thing to do is using the same number for
> both.

Thanks for all the comments.

Since the current tracepoints print the path length too by 
__trace_wb_cgroup_size and __trace_wbc_cgroup_size, but we can't get the 
path length if we switch to group ino. So, I'm supposed I have to drop 
all the *_size stuff.

And, when CONFIG_CGROUP_WRITEBACK is not enabled, 
__trace_wb_assign_cgroup and __trace_wbc_assign_cgroup return 
"strcpy(buf, "/")", so to get aligned with this, I need print out the 
ino of "/", right? But, the ROOT_INO may vary from different filesystems.

All of them will be addressed in V4, but it may experience some delay 
since I have to travel this week.

Regards,
Yang

> Thanks.