Re: Commit "new primitive: discard_new_inode()" introduces a problem

From: Kirill Tkhai
Date: Thu Aug 02 2018 - 12:02:30 EST


On 01.08.2018 19:34, Al Viro wrote:
> On Wed, Aug 01, 2018 at 07:19:35PM +0300, Kirill Tkhai wrote:
>> On 01.08.2018 19:16, Al Viro wrote:
>>> On Wed, Aug 01, 2018 at 05:11:51PM +0100, Al Viro wrote:
>>>> On Wed, Aug 01, 2018 at 06:43:56PM +0300, Kirill Tkhai wrote:
>>>>> #git status
>>>>> HEAD detached at 22dc9a168272
>>>>
>>>> Wait a sec - just that commit? With discard_new_inode() not even
>>>> used anywhere? Then any of those -ENOMEM is disguised ERR_PTR(-ESTALE)
>>>> from find_inode()/find_inode_fast(), i.e. an inode found by
>>>> iget5_locked() (your /etc is on ext4) with I_CREATING still set.
>>>
>>> iget_locked(), that is.
>
> OK, I see what's going on there. See if this fixes the problem:
>
> diff --git a/fs/dcache.c b/fs/dcache.c
> index 0e8e5de3c48a..b11f566bcd66 100644
> --- a/fs/dcache.c
> +++ b/fs/dcache.c
> @@ -1892,7 +1892,7 @@ void d_instantiate_new(struct dentry *entry, struct inode *inode)
> spin_lock(&inode->i_lock);
> __d_instantiate(entry, inode);
> WARN_ON(!(inode->i_state & I_NEW));
> - inode->i_state &= ~I_NEW;
> + inode->i_state &= ~I_NEW & ~I_CREATING;
> smp_mb();
> wake_up_bit(&inode->i_state, __I_NEW);
> spin_unlock(&inode->i_lock);

Yeah, this fixes the problem.

Tested-by: Kirill Tkhai <ktkhai@xxxxxxxxxxxxx>