linux-ext4 - Re: bdi has dirty inode after umount of ext4 fs in 3.4.83

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Message-ID: <20140325220938.GX4173@kvack.org>
Date:	Tue, 25 Mar 2014 18:09:38 -0400
From:	Benjamin LaHaise <bcrl@...ck.org>
To:	Jan Kara <jack@...e.cz>
Cc:	Alexander Viro <viro@...iv.linux.org.uk>,
	linux-fsdevel@...r.kernel.org, linux-ext4@...r.kernel.org
Subject: Re: bdi has dirty inode after umount of ext4 fs in 3.4.83

On Sun, Mar 23, 2014 at 02:14:16PM +0100, Jan Kara wrote:
>   So the dirty inode is almost certainly a block device inode. Another clue
> is that fsync(2) actually doesn't clean inode dirty state (especially not
> for block device inodes since that inode is a special one and fs usually
> doesn't get to inspecting it). sync(2) does in general clear inode dirty
> state because that's handled by flusher thread. However if ->sync_fs()
> dirties the block device inode, subsequent sync_blockdev() call only writes
> the data but doesn't clean the inode state. So even with sync(2) it can
> happen the block device inode remains dirty.

> In general inode dirty state isn't reliable. I_DIRTY_DATA can be set when
> inode is in fact clean. You have to use mapping_tagged(inode->i_mapping,
> PAGECACHE_TAG_DIRTY) to determine whether the inode has actually any dirty
> data.

That is indeed the case.  I checked the contents of the inode, and none of 
the buffers attached to that inode were dirty.

Is there any desire to fix this?  Seeing an inode on the b_dirty list that 
isn't really an inode that contains any data doesn't make a whole lot of 
sense.

		-ben
-- 
"Thought is the essence of where you are now."
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