Re: [PATCH 1/5 v2] vfs: Avoid creation of directory loops for corrupted filesystems

[Jan Kara <jack@suse.cz>]

On Wed 20-06-12 22:58:36, Jan Kara wrote:
> When a directory hierarchy is corrupted (e. g. due to a bit flip on the media),
> it can happen that it contains loops of directories. That creates possibilities
> for deadlock when locking directories.
> 
> Fix the problem by checking in d_splice_alias() that when we splice a
> directory, it does not have any other connected alias.
  Al, any opinion on this patch series?

									Honza

> Reported-by: Sami Liedes <sami.liedes@iki.fi>
> CC: "J. Bruce Fields" <bfields@fieldses.org>
> Signed-off-by: Jan Kara <jack@suse.cz>
> ---
>  fs/dcache.c |    5 +++++
>  1 files changed, 5 insertions(+), 0 deletions(-)
> 
>   Sorry guys, I'm resending this again because I messed up list address
> previously.
> 
> diff --git a/fs/dcache.c b/fs/dcache.c
> index 4046904..afe81fe 100644
> --- a/fs/dcache.c
> +++ b/fs/dcache.c
> @@ -1658,6 +1658,11 @@ struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry)
>  			d_move(new, dentry);
>  			iput(inode);
>  		} else {
> +			if (unlikely(!list_empty(&inode->i_dentry))) {
> +				spin_unlock(&inode->i_lock);
> +				iput(inode);
> +				return ERR_PTR(-EIO);
> +			}
>  			/* already taking inode->i_lock, so d_add() by hand */
>  			__d_instantiate(dentry, inode);
>  			spin_unlock(&inode->i_lock);
> -- 
> 1.7.1
> 
-- 
Jan Kara <jack@suse.cz>
SUSE Labs, CR