Re: [PATCH 2/2] Replace pid_t in autofs with struct pid reference

["Serge E. Hallyn" <serue@us.ibm.com>]

Quoting Eric W. Biederman (ebiederm@xmission.com):
> "Serge E. Hallyn" <serue@us.ibm.com> writes:
> 
> > So how about the following on top of the patch Cedric sent out?
> >
> > Subject: [PATCH] autofs4: store struct pids in autofs_waitqs
> > From: Serge Hallyn <serue@us.ibm.com>
> > Date: 1174412305 -0500
> >
> > Store struct pids in autofs_waitqs in place of pidnrs to prevent
> > pid overflow problems.
> 
> At first skip it doesn't looks ok.
> 
> > Signed-off-by: Serge E. Hallyn <serue@us.ibm.com>
> >
> > ---
> >
> >  fs/autofs4/autofs_i.h |   13 +++++++++++--
> >  fs/autofs4/waitq.c    |   15 ++++++++-------
> >  2 files changed, 19 insertions(+), 9 deletions(-)
> >
> > 86a5866c7672b88d48380504977496d5637642ab
> > diff --git a/fs/autofs4/autofs_i.h b/fs/autofs4/autofs_i.h
> > index 3ccec0a..5d119e3 100644
> > --- a/fs/autofs4/autofs_i.h
> > +++ b/fs/autofs4/autofs_i.h
> > @@ -79,8 +79,8 @@ struct autofs_wait_queue {
> >  	u64 ino;
> >  	uid_t uid;
> >  	gid_t gid;
> > -	pid_t pid;
> > -	pid_t tgid;
> > +	struct pid *pid;
> > +	struct pid *tgid;
> >  	/* This is for status reporting upon return */
> >  	int status;
> >  	atomic_t wait_ctr;
> > @@ -228,5 +228,14 @@ out:
> >  	return ret;
> >  }
> >  
> > +static void autofs_free_wait_queue(struct autofs_wait_queue *wq)
> > +{
> > +	if (wq->pid)
> > +		put_pid(wq->pid);
> > +	if (wq->tgid)
> > +		put_pid(wq->tgid);
> > +	kfree(wq);
> > +}
> > +
> >  void autofs4_dentry_release(struct dentry *);
> >  extern void autofs4_kill_sb(struct super_block *);
> > diff --git a/fs/autofs4/waitq.c b/fs/autofs4/waitq.c
> > index 9857543..4a9ad9b 100644
> > --- a/fs/autofs4/waitq.c
> > +++ b/fs/autofs4/waitq.c
> > @@ -141,8 +141,8 @@ static void autofs4_notify_daemon(struct
> >  		packet->ino = wq->ino;
> >  		packet->uid = wq->uid;
> >  		packet->gid = wq->gid;
> > -		packet->pid = wq->pid;
> > -		packet->tgid = wq->tgid;
> > +		packet->pid = pid_nr(wq->pid);
> > +		packet->tgid = pid_nr(wq->tgid);
> >  		break;
> 
> I'm assuming we build the packet in the process context of the
> daemon we are sending it to.  If not we have a problem here.

Yes this is data being sent to a userspace daemon (Ian pls correct me if
I'm wrong) so the pid_nr is the only thing we can send.

> >  	}
> >  	default:
> > @@ -292,8 +292,8 @@ int autofs4_wait(struct autofs_sb_info *
> >  		wq->ino = autofs4_get_ino(sbi);
> >  		wq->uid = current->uid;
> >  		wq->gid = current->gid;
> > -		wq->pid = pid_nr(task_pid(current));
> > -		wq->tgid = pid_nr(task_tgid(current));
> > +		wq->pid = get_pid(task_pid(current));
> > +		wq->tgid = get_pid(task_tgid(current));
> >  		wq->status = -EINTR; /* Status return if interrupted */
> >  		atomic_set(&wq->wait_ctr, 2);
> >  		mutex_unlock(&sbi->wq_mutex);
> > @@ -360,8 +360,9 @@ int autofs4_wait(struct autofs_sb_info *
> >  	status = wq->status;
> >  
> >  	/* Are we the last process to need status? */
> > -	if (atomic_dec_and_test(&wq->wait_ctr))
> > -		kfree(wq);
> > +	if (atomic_dec_and_test(&wq->wait_ctr)) {
> > +		autofs_free_wait_queue(wq);
> > +	}
> 
> Unnecessary braces....

Thanks.  Also needed another tweak in the .h file.  Here's a new patch.
Ian, please let me know if this (combined with the previous patch from
Cedric) is acceptable to you.

thanks,
-serge

Subject: [PATCH] autofs4: store struct pids in autofs_waitqs
From: Serge Hallyn <serue@us.ibm.com>
Date: 1174412305 -0500

Store struct pids in autofs_waitqs in place of pidnrs to prevent
pid overflow problems.

Signed-off-by: Serge E. Hallyn <serue@us.ibm.com>

---

 fs/autofs4/autofs_i.h |   13 +++++++++++--
 fs/autofs4/waitq.c    |   12 ++++++------
 2 files changed, 17 insertions(+), 8 deletions(-)

03944aae0b9cb4a36d091f275d2f2217447b27ec
diff --git a/fs/autofs4/autofs_i.h b/fs/autofs4/autofs_i.h
index 3ccec0a..8260743 100644
--- a/fs/autofs4/autofs_i.h
+++ b/fs/autofs4/autofs_i.h
@@ -79,8 +79,8 @@ struct autofs_wait_queue {
 	u64 ino;
 	uid_t uid;
 	gid_t gid;
-	pid_t pid;
-	pid_t tgid;
+	struct pid *pid;
+	struct pid *tgid;
 	/* This is for status reporting upon return */
 	int status;
 	atomic_t wait_ctr;
@@ -228,5 +228,14 @@ out:
 	return ret;
 }
 
+static inline void autofs_free_wait_queue(struct autofs_wait_queue *wq)
+{
+	if (wq->pid)
+		put_pid(wq->pid);
+	if (wq->tgid)
+		put_pid(wq->tgid);
+	kfree(wq);
+}
+
 void autofs4_dentry_release(struct dentry *);
 extern void autofs4_kill_sb(struct super_block *);
diff --git a/fs/autofs4/waitq.c b/fs/autofs4/waitq.c
index 9857543..6c696ea 100644
--- a/fs/autofs4/waitq.c
+++ b/fs/autofs4/waitq.c
@@ -141,8 +141,8 @@ static void autofs4_notify_daemon(struct
 		packet->ino = wq->ino;
 		packet->uid = wq->uid;
 		packet->gid = wq->gid;
-		packet->pid = wq->pid;
-		packet->tgid = wq->tgid;
+		packet->pid = pid_nr(wq->pid);
+		packet->tgid = pid_nr(wq->tgid);
 		break;
 	}
 	default:
@@ -292,8 +292,8 @@ int autofs4_wait(struct autofs_sb_info *
 		wq->ino = autofs4_get_ino(sbi);
 		wq->uid = current->uid;
 		wq->gid = current->gid;
-		wq->pid = pid_nr(task_pid(current));
-		wq->tgid = pid_nr(task_tgid(current));
+		wq->pid = get_pid(task_pid(current));
+		wq->tgid = get_pid(task_tgid(current));
 		wq->status = -EINTR; /* Status return if interrupted */
 		atomic_set(&wq->wait_ctr, 2);
 		mutex_unlock(&sbi->wq_mutex);
@@ -361,7 +361,7 @@ int autofs4_wait(struct autofs_sb_info *
 
 	/* Are we the last process to need status? */
 	if (atomic_dec_and_test(&wq->wait_ctr))
-		kfree(wq);
+		autofs_free_wait_queue(wq);
 
 	return status;
 }
@@ -390,7 +390,7 @@ int autofs4_wait_release(struct autofs_s
 	wq->status = status;
 
 	if (atomic_dec_and_test(&wq->wait_ctr))	/* Is anyone still waiting for this guy? */
-		kfree(wq);
+		autofs_free_wait_queue(wq);
 	else
 		wake_up_interruptible(&wq->queue);
 
-- 
1.1.6