Re: [PATCH] ovl: fix lookup of indexed hardlinks with metacopy

[Vivek Goyal <vgoyal@redhat.com>]

On Wed, Jul 15, 2020 at 04:38:08PM +0300, Amir Goldstein wrote:
> We recently moved setting inode flag OVL_UPPERDATA to ovl_lookup().
> 
> When looking up an overlay dentry, upperdentry may be found by index
> and not by name.  In that case, we fail to read the metacopy xattr
> and falsly set the OVL_UPPERDATA on the overlay inode.
> 
> This caused a regression in xfstest overlay/033 when run with
> OVERLAY_MOUNT_OPTIONS="-o metacopy=on".
> 
> Fixes: 28166ab3c875 ("ovl: initialize OVL_UPPERDATA in ovl_lookup()")
> Signed-off-by: Amir Goldstein <amir73il@gmail.com>

Reviewed-by: Vivek Goyal <vgoyal@redhat.com>

Good catch Amir. Thanks.


> ---
> 
> Miklos,
> 
> I just ran xfstests -g overlay/quick tests with metacopy enabled
> and one test failed.
> 
> Vivek,
> 
> Do you by any chance run this sort of test regularly?

No I don't. I will start testing this configuration. Actually I don't
have any automated setup and all the testing I do manually. I think
its time that atleast I have a script which runs bunch of tests
always.

> 
> You have asked about running unionmount tests with metacopy before.
> I just pushed a commit to my xfstests 'unionmount' branch:
>   7859f22b ovl: test unionmount tests with metacopy
> 
> It allows you to run xfstests -g overlay/union with
> OVERLAY_MOUNT_OPTIONS="-o metacopy=on", to excercise all the unionmount
> test configurations I created with metacopy enabled.

Nice, I will check it out. Will be nice if this gets pushed to
xfstest tree.

Thanks
Vivek

> 
> Maybe not so surprising that the sub-group overlay/union.nested tests
> fail with metacopy enabled. This is just a test setup bug and I pushed
> a fix commit to unionmount overlayfs-devel branch to fix it.
> 
> Thanks,
> Amir.
> 
>  fs/overlayfs/namei.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c
> index 3566282a9199..0c5a624600c1 100644
> --- a/fs/overlayfs/namei.c
> +++ b/fs/overlayfs/namei.c
> @@ -1073,6 +1073,10 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
>  			upperredirect = NULL;
>  			goto out_free_oe;
>  		}
> +		err = ovl_check_metacopy_xattr(upperdentry);
> +		if (err < 0)
> +			goto out_free_oe;
> +		uppermetacopy = err;
>  	}
>  
>  	if (upperdentry || ctr) {
> -- 
> 2.17.1
>