linux-ext4 - Re: [PATCH 3/5] ext4: Speedup ext4 orphan inode handling

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Message-ID: <20210816092340.GA24793@quack2.suse.cz>
Date:   Mon, 16 Aug 2021 11:23:40 +0200
From:   Jan Kara <jack@...e.cz>
To:     Theodore Ts'o <tytso@....edu>
Cc:     Jan Kara <jack@...e.cz>, linux-ext4@...r.kernel.org
Subject: Re: [PATCH 3/5] ext4: Speedup ext4 orphan inode handling

On Fri 13-08-21 11:26:45, Theodore Ts'o wrote:
> On Fri, Aug 13, 2021 at 02:34:34PM +0200, Jan Kara wrote:
> > Actually, in the orphan list code, we leave the inode in the on-disk list
> > but remove it from the in-memory list - see how
> > list_del_init(&ei->i_orphan) is called very early in ext4_orphan_del(). The
> > reason for this unconditional deletion is that if we do not remove the
> > inode from the in-memory orphan list, the filesystem will complain and
> > corrupt memory on unmount.
> > 
> > Also note that leaving inode in the on-disk orphan list actually does no
> > serious harm. Because the orphan cleanup code just checks i_nlink and
> > i_disksize and truncates inode down to current i_disksize and removes inode
> > completely if i_nlink is 0. So even if an inode on the orphan list gets
> > reused, orphan cleanup will just do nothing for it. So the worst problem
> > that will likely happen is that on-disk orphan linked list becomes
> > corrupted but there's no data loss AFAICT.
> > 
> > Is it clearer now or am I missing something?
> 
> Yes, you're right, I misread the code.  Thanks for clarifying.
> 
> Can you send the final spin of this patch set?  I think we're all set
> for this patch series.
> 
> Reviewed-by: Theodore Ts'o <tytso@....edu>

Thanks. I've posted v6 with all the updates.

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