ACK: [PATCH][EOAN/FOCAL/UNSTABLE] UBUNTU: SAUCE: overlayfs: fix shitfs special-casing

[Kleber Souza]

On 06.05.20 10:55, Christian Brauner wrote:
> BugLink: https://bugs.launchpad.net/bugs/1876645
> 
> When I picked up Andrei's patch I ported it wrong. We need to initialize
> realpath before dereferencing it obviously.
> 
> Cc: Stefan Bader <stefan.bader at canonical.com>
> Cc: Seth Forshee <seth.forshee at canonical.com>
> Cc: Kamal Mostafa <kamal at canonical.com>
> Cc: Kleber Sacilotto de Souza <kleber.souza at canonical.com>
> Cc: Andrei Vagin <avagin at gmail.com>
> Fixes: 4e1f6efeedae ("UBUNTU: SAUCE: overlayfs: use shiftfs hacks only with shiftfs as underlay")
> Link: https://bugs.launchpad.net/bugs/1857257
> Signed-off-by: Christian Brauner <christian.brauner at ubuntu.com>

The fix makes sense, I also ran our two testcases which were hitting this issue
and I couldn't reproduce it with this patch.

Thanks for the fix.

Acked-by: Kleber Sacilotto de Souza <kleber.souza at canonical.com>

> ---
>  fs/overlayfs/file.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c
> index 6bd7530efa5d..ccd5c2a0b044 100644
> --- a/fs/overlayfs/file.c
> +++ b/fs/overlayfs/file.c
> @@ -43,6 +43,7 @@ static struct file *ovl_open_realfile(const struct file *file,
>  	int flags = file->f_flags | O_NOATIME | FMODE_NONOTIFY;
>  
>  	old_cred = ovl_override_creds(inode->i_sb);
> +	ovl_path_real(file->f_path.dentry, &realpath);
>  	if (realpath.dentry->d_sb->s_magic == SHIFTFS_MAGIC)
>  		realfile = open_with_fake_path(&realpath, flags, realinode,
>  					       current_cred());
> 
> base-commit: c1661f985431696160f6f931361bd3af096cc3bf
>