[Devel] [RFC][PATCH 14/16] Introduce proc_mnt for pid_ns

[Pavel Emelianov]

sukadev at us.ibm.com wrote:
> Subject: Introduce proc_mnt for pid_ns
> 
> From: Dave Hansen <hansendc at us.ibm.com>
> 
> The following patch completes the removal of the global proc_mnt.
> It fetches the mnt on which to do dentry invalidations from the
> pid_namespace in which the task appears.
> 
> For now, there is only one pid namespace in mainline so this is
> straightforward.  In the -lxc tree we'll have to do something
> more complex.  The proc_flush_task() code takes a task, and
> needs to be able to find the corresponding proc superblocks on
> which that tasks's /proc/<pid> directories could appear.  We
> can tell in which pid namespaces a task appears, so I put a
> pointer from the pid namespace to the corresponding proc_mnt.
> 
> /proc currently has some special code to make sure that the root
> directory gets set up correctly.  It proc_mnt variable in order
> to find its way to the root inode.
> 
> Signed-off-by: Dave Hansen <haveblue at us.ibm.com>
> Signed-off-by: Sukadev Bhattiprolu <sukadev at us.ibm.com>
> ---
> 
>  fs/proc/base.c                |   32 ++++++++++++++++++++++++-
>  fs/proc/inode.c               |   11 +++++++-
>  fs/proc/root.c                |   52 ++++++++++++++++++++++++++++--------------
>  include/linux/pid_namespace.h |    1 
>  include/linux/proc_fs.h       |    1 
>  5 files changed, 75 insertions(+), 22 deletions(-)
> 

[snip]

> @@ -2071,6 +2084,21 @@ out:
>  	return;
>  }
>  
> +void proc_flush_task(struct task_struct *task)
> +{
> +	int i;
> +	struct pid *pid;
> +	struct upid* upid;
> +
> +	pid = task_pid(task);
> +	if (!pid)
> +		return;

The code below will never be called as task flushes all his pids
in __unhash_process() that happens before this. Or did I miss smth?

> +	upid = &pid->upid_list[0];
> +	for (i = 0; i < pid->num_upids; i++, upid++)
> +		proc_flush_task_from_pid_ns(task, upid->pid_ns);
> +}
> +
>  static struct dentry *proc_pid_instantiate(struct inode *dir,
>  					   struct dentry * dentry,
>  					   struct task_struct *task, const void *ptr)
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