Re: [PATCH 2/2] kernfs: dont take i_lock on revalidate

[Tejun Heo]

On Tue, Oct 18, 2022 at 10:32:49AM +0800, Ian Kent wrote:
> In kernfs_dop_revalidate() when the passed in dentry is negative the
> dentry directory is checked to see if it has changed and if so the
> negative dentry is discarded so it can refreshed. During this check
> the dentry inode i_lock is taken to mitigate against a possible
> concurrent rename.
> 
> But if it's racing with a rename, becuase the dentry is negative, it
> can't be the source it must be the target and it must be going to do
> a d_move() otherwise the rename will return an error.
> 
> In this case the parent dentry of the target will not change, it will
> be the same over the d_move(), only the source dentry parent may change
> so the inode i_lock isn't needed.
> 
> Signed-off-by: Ian Kent <raven@xxxxxxxxxx>

Acked-by: Tejun Heo <tj@xxxxxxxxxx>

Thanks.

-- 
tejun