Re: [PATCH] skip I_CLEAR state inodes

From: Eric Sandeen <sandeen@sandeen.net>
To: Wu Fengguang <fengguang.wu@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	LKML <linux-kernel@vger.kernel.org>, Jan Kara <jack@suse.cz>,
	Masayoshi MIZUMA <m.mizuma@jp.fujitsu.com>,
	"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
	"viro@zeniv.linux.org.uk" <viro@zeniv.linux.org.uk>,
	Nick Piggin <npiggin@suse.de>
Subject: Re: [PATCH] skip I_CLEAR state inodes
Date: Mon, 01 Jun 2009 16:38:35 -0500	[thread overview]
Message-ID: <4A244A5B.7070605@sandeen.net> (raw)
In-Reply-To: <20090324124001.GA25326@localhost>

Wu Fengguang wrote:
> Add I_CLEAR tests to drop_pagecache_sb(), generic_sync_sb_inodes() and
> add_dquot_ref().
> 
> clear_inode() will switch inode state from I_FREEING to I_CLEAR,
> and do so _outside_ of inode_lock. So any I_FREEING testing is
> incomplete without the testing of I_CLEAR.
> 
> Masayoshi MIZUMA first discovered the bug in drop_pagecache_sb() and
> Jan Kara reminds fixing the other two cases. Thanks!

Is there a reason it's not done for __sync_single_inode as well?

Jeff Layton asked the question and I'm following it up :)

__sync_single_inode currently only tests I_FREEING, but I think we are
safe because __sync_single_inode sets I_SYNC, and clear_inode waits for
I_SYNC to be cleared before it changes I_STATE.

On the other hand, testing I_CLEAR here probably would be safe anyway,
and it'd be bonus points for consistency?

Same basic question for generic_sync_sb_inodes, which has a
BUG_ON(inode->i_state & I_FREEING), seems like this could check I_CLWAR
as well?

Thanks,
-Eric