linux-kernel - Re: [PATCH (v4.18 regression fix)] vfs: don't evict uninitialized inode

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Message-ID: <20180706173540.GD30522@ZenIV.linux.org.uk>
Date:   Fri, 6 Jul 2018 18:35:40 +0100
From:   Al Viro <viro@...IV.linux.org.uk>
To:     Miklos Szeredi <mszeredi@...hat.com>
Cc:     linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH (v4.18 regression fix)] vfs: don't evict uninitialized
 inode

On Fri, Jul 06, 2018 at 05:35:48PM +0200, Miklos Szeredi wrote:
> iput() ends up calling ->evict() on new inode, which is not yet initialized
> by owning fs.  So use destroy_inode() instead.
> 
> Add to sb->s_inodes list only after the inode has been inserted into the
> hash.  The exact point at which the inode is added onto the sb list
> shouldn't matter as long as it is done while the inode is in the I_NEW
> state.
> 
> Reported-by: Al Viro <viro@...iv.linux.org.uk>
> Signed-off-by: Miklos Szeredi <mszeredi@...hat.com>
> Fixes: 80ea09a002bf ("vfs: factor out inode_insert5()")

Check 22dc9a168272 (new primitive: discard_new_inode()) in vfs.git; IMO yours
should go on top of that and I would seriously consider going for just
alloc_inode() - to hell with new_inode_pseudo().  I_CREATING gives an easy
way for insert_inode5() to decide whether we need to move into ->i_sb_list...