Re: [PATCH 7/7] writeback: Avoid iput() from flusher thread

[Christoph Hellwig <hch@infradead.org>]

> - * Wait for writeback on an inode to complete.
> + * Wait for writeback on an inode to complete. Called with i_lock held.
> + * Caller must make sure inode cannot go away when we drop i_lock.
>   */
> -static void inode_wait_for_writeback(struct inode *inode)
> +void inode_wait_for_writeback(struct inode *inode)
>  {
>  	DEFINE_WAIT_BIT(wq, &inode->i_state, __I_SYNC);
>  	wait_queue_head_t *wqh;
> @@ -340,6 +341,26 @@ static void inode_wait_for_writeback(struct inode *inode)
>  	}
>  }

This needs way better documentation, preferably using kernel doc.

I also suspect we should rename inode_wait_for_writeback to
__inode_wait_for_writeback and make inode_wait_for_writeback the public
wrapper that takes i_lock.

> diff --git a/fs/inode.c b/fs/inode.c
> index d3ebdbe..3869714 100644
> --- a/fs/inode.c
> +++ b/fs/inode.c
> @@ -510,7 +510,6 @@ void end_writeback(struct inode *inode)
>  	BUG_ON(!list_empty(&inode->i_data.private_list));
>  	BUG_ON(!(inode->i_state & I_FREEING));
>  	BUG_ON(inode->i_state & I_CLEAR);
> -	inode_sync_wait(inode);
>  	/* don't need i_lock here, no concurrent mods to i_state */
>  	inode->i_state = I_FREEING | I_CLEAR;
>  }

end_writeback is really misnamed now and needs a better name.