Re: [PATCH 7/9] fsnotify: use existed call_srcu()

[Lai Jiangshan <laijs@cn.fujitsu.com>]

[Ping]

Hi, Eric Paris

Could you review this patch?

Thanks,
Lai

On 03/16/2013 12:50 AM, Lai Jiangshan wrote:
> fsnotify implements its own call_srcu() by:
> 	dedicated thread + synchronize_srcu()
> 
> But srcu provides call_srcu() now, so we should convert them to use
> existed call_srcu() and remove the thread.
> 
> Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
> Cc: Eric Paris <eparis@parisplace.org>
> ---
>  fs/notify/mark.c                 |   59 ++++++-------------------------------
>  include/linux/fsnotify_backend.h |    2 +-
>  2 files changed, 11 insertions(+), 50 deletions(-)
> 
> diff --git a/fs/notify/mark.c b/fs/notify/mark.c
> index aeededc..af5f0e1 100644
> --- a/fs/notify/mark.c
> +++ b/fs/notify/mark.c
> @@ -98,9 +98,6 @@
>  #include "fsnotify.h"
>  
>  DEFINE_SRCU(fsnotify_mark_srcu);
> -static DEFINE_SPINLOCK(destroy_lock);
> -static LIST_HEAD(destroy_list);
> -static DECLARE_WAIT_QUEUE_HEAD(destroy_waitq);
>  
>  void fsnotify_get_mark(struct fsnotify_mark *mark)
>  {
> @@ -116,6 +113,14 @@ void fsnotify_put_mark(struct fsnotify_mark *mark)
>  	}
>  }
>  
> +static void fsnotify_destroy_mark_rcu(struct rcu_head *rcu)
> +{
> +	struct fsnotify_mark *mark;
> +
> +	mark = container_of(rcu, struct fsnotify_mark, rcu);
> +	fsnotify_put_mark(mark);
> +}
> +
>  /*
>   * Any time a mark is getting freed we end up here.
>   * The caller had better be holding a reference to this mark so we don't actually
> @@ -155,10 +160,7 @@ void fsnotify_destroy_mark_locked(struct fsnotify_mark *mark,
>  	/* release lock temporarily */
>  	mutex_unlock(&group->mark_mutex);
>  
> -	spin_lock(&destroy_lock);
> -	list_add(&mark->destroy_list, &destroy_list);
> -	spin_unlock(&destroy_lock);
> -	wake_up(&destroy_waitq);
> +	call_srcu(&fsnotify_mark_srcu, &mark->rcu, fsnotify_destroy_mark_rcu);
>  	/*
>  	 * We don't necessarily have a ref on mark from caller so the above destroy
>  	 * may have actually freed it, unless this group provides a 'freeing_mark'
> @@ -273,11 +275,7 @@ err:
>  	atomic_dec(&group->num_marks);
>  
>  	spin_unlock(&mark->lock);
> -
> -	spin_lock(&destroy_lock);
> -	list_add(&mark->destroy_list, &destroy_list);
> -	spin_unlock(&destroy_lock);
> -	wake_up(&destroy_waitq);
> +	call_srcu(&fsnotify_mark_srcu, &mark->rcu, fsnotify_destroy_mark_rcu);
>  
>  	return ret;
>  }
> @@ -342,40 +340,3 @@ void fsnotify_init_mark(struct fsnotify_mark *mark,
>  	atomic_set(&mark->refcnt, 1);
>  	mark->free_mark = free_mark;
>  }
> -
> -static int fsnotify_mark_destroy(void *ignored)
> -{
> -	struct fsnotify_mark *mark, *next;
> -	LIST_HEAD(private_destroy_list);
> -
> -	for (;;) {
> -		spin_lock(&destroy_lock);
> -		/* exchange the list head */
> -		list_replace_init(&destroy_list, &private_destroy_list);
> -		spin_unlock(&destroy_lock);
> -
> -		synchronize_srcu(&fsnotify_mark_srcu);
> -
> -		list_for_each_entry_safe(mark, next, &private_destroy_list, destroy_list) {
> -			list_del_init(&mark->destroy_list);
> -			fsnotify_put_mark(mark);
> -		}
> -
> -		wait_event_interruptible(destroy_waitq, !list_empty(&destroy_list));
> -	}
> -
> -	return 0;
> -}
> -
> -static int __init fsnotify_mark_init(void)
> -{
> -	struct task_struct *thread;
> -
> -	thread = kthread_run(fsnotify_mark_destroy, NULL,
> -			     "fsnotify_mark");
> -	if (IS_ERR(thread))
> -		panic("unable to start fsnotify mark destruction thread.");
> -
> -	return 0;
> -}
> -device_initcall(fsnotify_mark_init);
> diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h
> index d5b0910..3d435eb 100644
> --- a/include/linux/fsnotify_backend.h
> +++ b/include/linux/fsnotify_backend.h
> @@ -296,7 +296,7 @@ struct fsnotify_mark {
>  #define FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY	0x08
>  #define FSNOTIFY_MARK_FLAG_ALIVE		0x10
>  	unsigned int flags;		/* vfsmount or inode mark? */
> -	struct list_head destroy_list;
> +	struct rcu_head rcu;
>  	void (*free_mark)(struct fsnotify_mark *mark); /* called on final put+free */
>  };
>