linux-kernel - Re: The bug of iput() removal from flusher thread?

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Message-ID: <20121121024405.GN2591@dastard>
Date:	Wed, 21 Nov 2012 13:44:05 +1100
From:	Dave Chinner <david@...morbit.com>
To:	Jan Kara <jack@...e.cz>
Cc:	OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>,
	Al Viro <viro@...iv.linux.org.uk>,
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: The bug of iput() removal from flusher thread?

On Wed, Nov 21, 2012 at 02:48:51AM +0100, Jan Kara wrote:
> 
> diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
> index 51ea267..3e3422f 100644
> --- a/fs/fs-writeback.c
> +++ b/fs/fs-writeback.c
> @@ -228,6 +228,8 @@ static void requeue_io(struct inode *inode, struct bdi_writeback *wb)
>  static void inode_sync_complete(struct inode *inode)
>  {
>  	inode->i_state &= ~I_SYNC;
> +	/* If inode is clean an unused, put it into LRU now... */
> +	inode_add_lru(inode);
>  	/* Waiters must see I_SYNC cleared before being woken up */
>  	smp_mb();
>  	wake_up_bit(&inode->i_state, __I_SYNC);
> diff --git a/fs/inode.c b/fs/inode.c
> index b03c719..8f6396f 100644
> --- a/fs/inode.c
> +++ b/fs/inode.c
> @@ -408,6 +408,19 @@ static void inode_lru_list_add(struct inode *inode)
>  	spin_unlock(&inode->i_sb->s_inode_lru_lock);
>  }
>  
> +/*
> + * Add inode to LRU if needed (inode is unused and clean).
> + *
> + * Needs inode->i_lock held.
> + */
> +void inode_add_lru(struct inode *inode)
> +{
> +	if (!(inode->i_state & (I_DIRTY | I_FREEING | I_SYNC)) &&
> +	    !atomic_read(&inode->i_count) && inode->i_sb->s_flags & MS_ACTIVE)
> +		inode_lru_list_add(inode);

Needs to avoid I_WILL_FREE as well. There's no point putting it on
the LRU if we are writing from iput_final()....

Otherwise looks OK.

Cheers,

Dave.
-- 
Dave Chinner
david@...morbit.com
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