linux-ext4 - Re: [PATCH 2/4 v2] ext4: Remove unnecessary wait_event ext4_run_lazyinit

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Date:	Fri, 20 May 2011 11:09:05 +0200 (CEST)
From:	Lukas Czerner <lczerner@...hat.com>
To:	Eric Sandeen <sandeen@...hat.com>
cc:	Lukas Czerner <lczerner@...hat.com>, linux-ext4@...r.kernel.org,
	tytso@....edu
Subject: Re: [PATCH 2/4 v2] ext4: Remove unnecessary wait_event
 ext4_run_lazyinit_thread()

On Thu, 19 May 2011, Eric Sandeen wrote:

> On 5/9/11 10:57 AM, Lukas Czerner wrote:
> > For some reason we have been waiting for lazyinit thread to start in the
> > ext4_run_lazyinit_thread() but it is not needed anymore so get rid of
> > it. We can also remove li_task and li_wait_task since it is not used
> > anymore.
> > 
> > Signed-off-by: Lukas Czerner <lczerner@...hat.com>
> 
> Can you add to the changelog why this is "not needed anymore?"
> What changed?  Was there any reason that it was waiting before,
> or was that just unnecessary complexity?  I don't think
> there is a need to wait for the thread to ping us back
> after calling kthread_run() but I just wonder why it was
> there in the first place...

Ok, I'll try to figure that out :) But probably just unnecessary
complexity :)

Thanks for the review!
-Lukas

> 
> Other than that, seems fine, so:
> 
> Reviewed-by: Eric Sandeen <sandeen@...hat.com>
> 
> > ---
> >  fs/ext4/ext4.h  |    2 --
> >  fs/ext4/super.c |   10 ----------
> >  2 files changed, 0 insertions(+), 12 deletions(-)
> > 
> > diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
> > index 1e37c09..8689f97 100644
> > --- a/fs/ext4/ext4.h
> > +++ b/fs/ext4/ext4.h
> > @@ -1590,8 +1590,6 @@ void ext4_get_group_no_and_offset(struct super_block *sb, ext4_fsblk_t blocknr,
> >   */
> >  struct ext4_lazy_init {
> >  	unsigned long		li_state;
> > -	wait_queue_head_t	li_wait_task;
> > -	struct task_struct	*li_task;
> >  	struct list_head	li_request_list;
> >  	struct mutex		li_list_mtx;
> >  };
> > diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> > index f0e4c3a..6ccf0e2 100644
> > --- a/fs/ext4/super.c
> > +++ b/fs/ext4/super.c
> > @@ -2754,9 +2754,6 @@ static int ext4_lazyinit_thread(void *arg)
> >  
> >  	BUG_ON(NULL == eli);
> >  
> > -	eli->li_task = current;
> > -	wake_up(&eli->li_wait_task);
> > -
> >  cont_thread:
> >  	while (true) {
> >  		next_wakeup = MAX_JIFFY_OFFSET;
> > @@ -2819,9 +2816,6 @@ exit_thread:
> >  		goto cont_thread;
> >  	}
> >  	mutex_unlock(&eli->li_list_mtx);
> > -	eli->li_task = NULL;
> > -	wake_up(&eli->li_wait_task);
> > -
> >  	kfree(ext4_li_info);
> >  	ext4_li_info = NULL;
> >  	mutex_unlock(&ext4_li_mtx);
> > @@ -2858,8 +2852,6 @@ static int ext4_run_lazyinit_thread(void)
> >  		return err;
> >  	}
> >  	ext4_li_info->li_state |= EXT4_LAZYINIT_RUNNING;
> > -
> > -	wait_event(ext4_li_info->li_wait_task, ext4_li_info->li_task != NULL);
> >  	return 0;
> >  }
> >  
> > @@ -2894,11 +2886,9 @@ static int ext4_li_info_new(void)
> >  	if (!eli)
> >  		return -ENOMEM;
> >  
> > -	eli->li_task = NULL;
> >  	INIT_LIST_HEAD(&eli->li_request_list);
> >  	mutex_init(&eli->li_list_mtx);
> >  
> > -	init_waitqueue_head(&eli->li_wait_task);
> >  	eli->li_state |= EXT4_LAZYINIT_QUIT;
> >  
> >  	ext4_li_info = eli;
> 
> 

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