[EMAIL PROTECTED] wrote:
> From: [EMAIL PROTECTED]
> Subject: [PATCH 17/17] Pid-NS(V3) Introduce proc_mnt for pid_ns
>
> 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.
>
> Changelog:
>
> 2.6.22-rc4-mm2-pidns1:
>
> - Call proc_fill_super once per pid namespace
> - Call proc_flush_task() before detaching a task's 'struct pid'.
> - Get a reference to pid namespace when mounting/remounting /proc.
> Put this reference when unmounting.
>
> Signed-off-by: Dave Hansen <[EMAIL PROTECTED]>
> Signed-off-by: Sukadev Bhattiprolu <[EMAIL PROTECTED]>
> ---
>
> fs/proc/base.c | 30 ++++++++++++++++++-
> fs/proc/inode.c | 12 ++++++-
> fs/proc/root.c | 65
> ++++++++++++++++++++++++++++++------------
> include/linux/pid_namespace.h | 1
> include/linux/proc_fs.h | 1
> kernel/exit.c | 2 -
> 6 files changed, 87 insertions(+), 24 deletions(-)
>
[snip]
> @@ -55,12 +90,6 @@ void __init proc_root_init(void)
> err = register_filesystem(&proc_fs_type);
> if (err)
> return;
> - proc_mnt = kern_mount(&proc_fs_type);
> - err = PTR_ERR(proc_mnt);
> - if (IS_ERR(proc_mnt)) {
> - unregister_filesystem(&proc_fs_type);
> - return;
> - }
Wow! Is this safe? Everyone expexts proc_mnt to be not NULL.
> proc_misc_init();
> proc_net = proc_mkdir("net", NULL);
> proc_net_stat = proc_mkdir("net/stat", NULL);
[snip]
> Index: lx26-22-rc4-mm2/kernel/exit.c
> ===================================================================
> --- lx26-22-rc4-mm2.orig/kernel/exit.c 2007-06-16 04:15:23.000000000
> -0700
> +++ lx26-22-rc4-mm2/kernel/exit.c 2007-06-16 04:15:23.000000000 -0700
> @@ -157,6 +157,7 @@ void release_task(struct task_struct * p
> struct task_struct *leader;
> int zap_leader;
> repeat:
> + proc_flush_task(p);
Such a flush won't actually remove *any* dentries from the tree and thus
may be omitted.
> atomic_dec(&p->user->processes);
> write_lock_irq(&tasklist_lock);
> ptrace_unlink(p);
> @@ -185,7 +186,6 @@ repeat:
> }
>
> write_unlock_irq(&tasklist_lock);
> - proc_flush_task(p);
> release_thread(p);
> call_rcu(&p->rcu, delayed_put_task_struct);
>
>
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