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

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Message-ID: <20121121013055.GF10507@quack.suse.cz>
Date:	Wed, 21 Nov 2012 02:30:55 +0100
From:	Jan Kara <jack@...e.cz>
To:	Dave Chinner <david@...morbit.com>
Cc:	Jan Kara <jack@...e.cz>,
	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 21-11-12 09:37:41, Dave Chinner wrote:
> On Mon, Nov 19, 2012 at 08:41:02PM +0100, Jan Kara wrote:
> > diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
> > index 51ea267..ed7613b 100644
> > --- a/fs/fs-writeback.c
> > +++ b/fs/fs-writeback.c
> > @@ -227,6 +227,9 @@ static void requeue_io(struct inode *inode, struct bdi_writeback *wb)
> >  
> >  static void inode_sync_complete(struct inode *inode)
> >  {
> > +	/* If inode is clean an unused, put it into LRU now.  */
> > +	if (!(inode->i_state & I_DIRTY) && !atomic_read(&inode->i_count))
> > +		inode_lru_list_add(inode);
> 
> Unsafe. Has to avoid I_FREEING|I_WILL_FREE (see warnings at start of
> writeback_single_inode()).
> 
> Also, if you do this after clearing the I_SYNC flag, you can use
> exactly the same logic as iput_final(). A helper function could be
> used for both cases at that point, and....
  Agreed. That's what I do in the current version of the patch (not posted
yet).

								Honza
-- 
Jan Kara <jack@...e.cz>
SUSE Labs, CR
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