Subject: Re: linux-next: OOPS at boot time

From: Al Viro <[email-masked]>
Date: Wed, 21 Jul 2010 18:49:52 +0100

On Wed, Jul 21, 2010 at 02:11:17PM +0200, Jan Kara wrote:
>   Thanks for bisecting this. The patch series indeed seems to uncover
> some discrepancies.
>   Ext3 has always dirtied inode in it's ->delete_inode method (via quota
> code). But previously clear_inode() just overwrote the state with I_CLEAR
> and thus we never saw the BUG_ON. After Al's patches, i_state is set in
> end_writeback() which happens earlier. In particular it happens before
> ext3_free_inode() which dirties the inode through quota code while freeing
> xattrs - they are accounted in i_blocks, so i_blocks are updated during
> freeing and inode is dirtied.
>   Actually, ext3_mark_inode_dirty() called during each mark_inode_dirty()
> call writes the inode state to the journal so the dirty flag in the inode
> state is in fact stale and overwriting it with I_CLEAR never mattered. In
> this sense, the BUG_ON triggered is a false positive. But I believe this is
> a separate story.
>   I'm not sure how to really fix this. It seems a bit premature to me to
> mark inode as I_CLEAR before the filesystem is actually done with it. So
> maybe the line
>   inode->i_state = I_FREEING | I_CLEAR;
> should be moved to evict() fuction?

Nope.  I_CLEAR is "no async calls from vfs anymore; it's under complete
fs control and is about to die now".

In any case, I'll post a dumb replacement for ext3 after I verify it on
the laptop I have with me.  Should be in an hour or so (the damn thing is
_slow_).