Re: [PATCH RFC v2 5/6] inode: port __I_LRU_ISOLATING to var event

[Jeff Layton <jlayton@kernel.org>]

On Wed, 2024-08-21 at 17:47 +0200, Christian Brauner wrote:
> Port the __I_LRU_ISOLATING mechanism to use the new var event mechanism.
> 
> Signed-off-by: Christian Brauner <brauner@kernel.org>
> ---
>  fs/inode.c | 26 +++++++++++++++++---------
>  1 file changed, 17 insertions(+), 9 deletions(-)
> 
> diff --git a/fs/inode.c b/fs/inode.c
> index d18e1567c487..c8a5c63dc980 100644
> --- a/fs/inode.c
> +++ b/fs/inode.c
> @@ -510,8 +510,7 @@ static void inode_unpin_lru_isolating(struct inode *inode)
>  	spin_lock(&inode->i_lock);
>  	WARN_ON(!(inode->i_state & I_LRU_ISOLATING));
>  	inode->i_state &= ~I_LRU_ISOLATING;
> -	smp_mb();
> -	wake_up_bit(&inode->i_state, __I_LRU_ISOLATING);
> +	inode_wake_up_bit(inode, __I_LRU_ISOLATING);
>  	spin_unlock(&inode->i_lock);
>  }
>  
> @@ -519,13 +518,22 @@ static void inode_wait_for_lru_isolating(struct inode *inode)
>  {
>  	lockdep_assert_held(&inode->i_lock);
>  	if (inode->i_state & I_LRU_ISOLATING) {
> -		DEFINE_WAIT_BIT(wq, &inode->i_state, __I_LRU_ISOLATING);
> -		wait_queue_head_t *wqh;
> -
> -		wqh = bit_waitqueue(&inode->i_state, __I_LRU_ISOLATING);
> -		spin_unlock(&inode->i_lock);
> -		__wait_on_bit(wqh, &wq, bit_wait, TASK_UNINTERRUPTIBLE);
> -		spin_lock(&inode->i_lock);
> +		struct wait_bit_queue_entry wqe;
> +		struct wait_queue_head *wq_head;
> +
> +		wq_head = inode_bit_waitqueue(&wqe, inode, __I_LRU_ISOLATING);
> +		for (;;) {
> +			prepare_to_wait_event(wq_head, &wqe.wq_entry,
> +					      TASK_UNINTERRUPTIBLE);
> +			if (inode->i_state & I_LRU_ISOLATING) {
> +				spin_unlock(&inode->i_lock);
> +				schedule();
> +				spin_lock(&inode->i_lock);
> +				continue;
> +			}
> +			break;
> +		}

nit: personally, I'd prefer this, since you wouldn't need the brackets
or the continue:

			if (!(inode->i_state & LRU_ISOLATING))
				break;
			spin_unlock();
			schedule();
			...

> +		finish_wait(wq_head, &wqe.wq_entry);
>  		WARN_ON(inode->i_state & I_LRU_ISOLATING);
>  	}
>  }
> 

-- 
Jeff Layton <jlayton@kernel.org>