[Devel] Re: [PATCH 2/4] proc: Simplify proc_get_sb.

[Eric W. Biederman]

Pavel Emelyanov <xemul at openvz.org> writes:

> Eric W. Biederman wrote:
>> The idle_thread now has a struct pid, so we can always find out know
>> the pid of the child_reaper before we mount proc.
>> 
>> Therefore we can remove the special cases for getting the pid of the
>> child_reaper from proc_get_sb.
>> 
>> Signed-off-by: Eric W. Biederman <ebiederm at xmission.com>
>> ---
>>  fs/proc/root.c |   17 +----------------
>>  1 files changed, 1 insertions(+), 16 deletions(-)
>> 
>> diff --git a/fs/proc/root.c b/fs/proc/root.c
>> index 81f99e6..f442967 100644
>> --- a/fs/proc/root.c
>> +++ b/fs/proc/root.c
>> @@ -46,17 +46,6 @@ static int proc_get_sb(struct file_system_type *fs_type,
>>  	struct pid_namespace *ns;
>>  	struct proc_inode *ei;
>>  
>> -	if (proc_mnt) {
>> -		/* Seed the root directory with a pid so it doesn't need
>> -		 * to be special in base.c.  I would do this earlier but
>> -		 * the only task alive when /proc is mounted the first time
>> -		 * is the init_task and it doesn't have any pids.
>> -		 */
>> -		ei = PROC_I(proc_mnt->mnt_sb->s_root->d_inode);
>> -		if (!ei->pid)
>> -			ei->pid = find_get_pid(1);
>> -	}
>> -
>>  	if (flags & MS_KERNMOUNT)
>>  		ns = (struct pid_namespace *)data;
>>  	else
>> @@ -76,11 +65,7 @@ static int proc_get_sb(struct file_system_type *fs_type,
>>  		}
>>  
>>  		ei = PROC_I(sb->s_root->d_inode);
>> -		if (!ei->pid) {
>> -			rcu_read_lock();
>> -			ei->pid = get_pid(find_pid_ns(1, ns));
>> -			rcu_read_unlock();
>> -		}
>> +		ei->pid = get_pid(ns->child_reaper);
>
> That's not git-bisect safe - you move the child_reaper initialization
> before the call to prepare_proc only in the 4th patch.

Bugger.  I had overlooked that dependency.  So patch 4 really should have been
patch 2.

Eric
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