Re: [RFC V1] Replace pid_t in autofs4 with struct pid reference.

["Serge E. Hallyn" <serge.hallyn-Z7WLFzj8eWMS+FvcfC7Uqw@public.gmane.org>]

Quoting Daniel Lezcano (daniel.lezcano-GANU6spQydw@public.gmane.org):
> I resurect and refreshed this old patch from
> https://lists.linux-foundation.org/pipermail/containers/2007-February/003726.html
> 
> This patch makes automount to work within a container.
> 
> Make autofs4 container-friendly by caching struct pid reference rather
> than pid_t and using pid_nr() to retreive a task's pid_t.
> 
> ChangeLog:
> 
> V1:
> 	- fixed pgrp option in parse_options
> 	- used get_task_pid(current, PIDTYPE_PGID) instead of task_pgrp
> 	- fixed how is passed the 'pgrp' argument autofs4_fill_super
> 	- fixed bad pid conversion, was pid_vnr not pid_nr in autofs4_wait
> V0:
> 	- Refreshed against linux-next (added dev-ioctl.c)
> 	- Fix Eric Biederman's comments - Use find_get_pid() to hold a
> 	  reference to oz_pgrp and release while unmounting; separate out
> 	  changes to autofs and autofs4.
> 	- Also rollback my earlier change to autofs_wait_queue (pid and tgid
> 	  in the wait queue are just used to write to a userspace daemon's
> 	  pipe).
>         - Fix Cedric's comments: retain old prototype of parse_options()
>           and move necessary change to its caller.
> 
> Signed-off-by: Sukadev Bhattiprolu <sukadev-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>
> Signed-off-by: Daniel Lezcano <daniel.lezcano-GANU6spQydw@public.gmane.org>
> Cc: Ian Kent <raven-PKsaG3nR2I+sTnJN9+BGXg@public.gmane.org>
> Cc: Cedric Le Goater <clg-NmTC/0ZBporQT0dZR+AlfA@public.gmane.org>
> Cc: Dave Hansen <haveblue-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>
> Cc: Serge E. Hallyn <serge.hallyn-Z7WLFzj8eWMS+FvcfC7Uqw@public.gmane.org>

Acked-by: Serge E. Hallyn <serge.hallyn-Z7WLFzj8eWMS+FvcfC7Uqw@public.gmane.org>

Thanks, Daniel, this looks good!  Thanks for pushing this needed fix.

-serge