[Devel] Re: [PATCH 6/12] gfs2: make gfs2_glock.gl_owner_pid be a struct pid *

[Steven Whitehouse]

Hi,

Would you like me to take these two GFS2 patches into my git tree for
the next merge window, or are you intending that these should go to
Linus in this merge window? Either way I'm happy to add my:

Signed-off-by: Steven Whitehouse <swhiteho at redhat.com>

Steve.

On Tue, 2008-01-29 at 16:55 +0300, Pavel Emelyanov wrote:
> The gl_owner_pid field is used to get the lock owning
> task by its pid, so make it in a proper manner, i.e.
> by using the struct pid pointer and pid_task() function.
> 
> The pid_task() becomes exported for the gfs2 module.
> 
> Signed-off-by: Pavel Emelyanov <xemul at openvz.org>
> 
> ---
>  fs/gfs2/glock.c  |   19 ++++++++++++-------
>  fs/gfs2/incore.h |    2 +-
>  2 files changed, 13 insertions(+), 8 deletions(-)
> 
> diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
> index 80e09c5..5fe585f 100644
> --- a/fs/gfs2/glock.c
> +++ b/fs/gfs2/glock.c
> @@ -334,7 +334,7 @@ int gfs2_glock_get(struct gfs2_sbd *sdp, u64 number,
>  	gl->gl_state = LM_ST_UNLOCKED;
>  	gl->gl_demote_state = LM_ST_EXCLUSIVE;
>  	gl->gl_hash = hash;
> -	gl->gl_owner_pid = 0;
> +	gl->gl_owner_pid = NULL;
>  	gl->gl_ip = 0;
>  	gl->gl_ops = glops;
>  	gl->gl_req_gh = NULL;
> @@ -631,7 +631,7 @@ static void gfs2_glmutex_lock(struct gfs2_glock *gl)
>  		wait_on_holder(&gh);
>  		gfs2_holder_uninit(&gh);
>  	} else {
> -		gl->gl_owner_pid = current->pid;
> +		gl->gl_owner_pid = get_pid(task_pid(current));
>  		gl->gl_ip = (unsigned long)__builtin_return_address(0);
>  		spin_unlock(&gl->gl_spin);
>  	}
> @@ -652,7 +652,7 @@ static int gfs2_glmutex_trylock(struct gfs2_glock *gl)
>  	if (test_and_set_bit(GLF_LOCK, &gl->gl_flags)) {
>  		acquired = 0;
>  	} else {
> -		gl->gl_owner_pid = current->pid;
> +		gl->gl_owner_pid = get_pid(task_pid(current));
>  		gl->gl_ip = (unsigned long)__builtin_return_address(0);
>  	}
>  	spin_unlock(&gl->gl_spin);
> @@ -668,12 +668,17 @@ static int gfs2_glmutex_trylock(struct gfs2_glock *gl)
>  
>  static void gfs2_glmutex_unlock(struct gfs2_glock *gl)
>  {
> +	struct pid *pid;
> +
>  	spin_lock(&gl->gl_spin);
>  	clear_bit(GLF_LOCK, &gl->gl_flags);
> -	gl->gl_owner_pid = 0;
> +	pid = gl->gl_owner_pid;
> +	gl->gl_owner_pid = NULL;
>  	gl->gl_ip = 0;
>  	run_queue(gl);
>  	spin_unlock(&gl->gl_spin);
> +
> +	put_pid(pid);
>  }
>  
>  /**
> @@ -1877,13 +1882,13 @@ static int dump_glock(struct glock_iter *gi, struct gfs2_glock *gl)
>  	print_dbg(gi, "  gl_ref = %d\n", atomic_read(&gl->gl_ref));
>  	print_dbg(gi, "  gl_state = %u\n", gl->gl_state);
>  	if (gl->gl_owner_pid) {
> -		gl_owner = find_task_by_pid(gl->gl_owner_pid);
> +		gl_owner = pid_task(gl->gl_owner_pid, PIDTYPE_PID);
>  		if (gl_owner)
>  			print_dbg(gi, "  gl_owner = pid %d (%s)\n",
> -				  gl->gl_owner_pid, gl_owner->comm);
> +				  pid_nr(gl->gl_owner_pid), gl_owner->comm);
>  		else
>  			print_dbg(gi, "  gl_owner = %d (ended)\n",
> -				  gl->gl_owner_pid);
> +				  pid_nr(gl->gl_owner_pid));
>  	} else
>  		print_dbg(gi, "  gl_owner = -1\n");
>  	print_dbg(gi, "  gl_ip = %lu\n", gl->gl_ip);
> diff --git a/fs/gfs2/incore.h b/fs/gfs2/incore.h
> index 1339996..8ad1c3f 100644
> --- a/fs/gfs2/incore.h
> +++ b/fs/gfs2/incore.h
> @@ -182,7 +182,7 @@ struct gfs2_glock {
>  	unsigned int gl_hash;
>  	unsigned int gl_demote_state; /* state requested by remote node */
>  	unsigned long gl_demote_time; /* time of first demote request */
> -	pid_t gl_owner_pid;
> +	struct pid *gl_owner_pid;
>  	unsigned long gl_ip;
>  	struct list_head gl_holders;
>  	struct list_head gl_waiters1;	/* HIF_MUTEX */
> diff --git a/kernel/pid.c b/kernel/pid.c
> index e4e5fc8..4776915 100644
> --- a/kernel/pid.c
> +++ b/kernel/pid.c
> @@ -367,6 +367,7 @@ struct task_struct *pid_task(struct pid *pid, enum pid_type type)
>  	}
>  	return result;
>  }
> +EXPORT_SYMBOL(pid_task);
>  
>  /*
>   * Must be called under rcu_read_lock() or with tasklist_lock read-held.