On Mon, Oct 2, 2023 at 5:36 AM Al Viro <viro@xxxxxxxxxxxxxxxxxx> wrote:
>
> d_inode_rcu() is right - we might be in rcu pathwalk;
> however, OVL_E() hides plain d_inode() on the same dentry...
>
> Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Reviewed-by: Amir Goldstein <amir73il@xxxxxxxxx>
However, ovl_lowerstack(oe) does not appear to be stable in RCU walk...
> ---
> fs/overlayfs/super.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
> index f09184b865ec..905d3aaf4e55 100644
> --- a/fs/overlayfs/super.c
> +++ b/fs/overlayfs/super.c
> @@ -104,8 +104,8 @@ static int ovl_revalidate_real(struct dentry *d, unsigned int flags, bool weak)
> static int ovl_dentry_revalidate_common(struct dentry *dentry,
> unsigned int flags, bool weak)
> {
> - struct ovl_entry *oe = OVL_E(dentry);
> - struct ovl_path *lowerstack = ovl_lowerstack(oe);
> + struct ovl_entry *oe;
> + struct ovl_path *lowerstack;
> struct inode *inode = d_inode_rcu(dentry);
> struct dentry *upper;
> unsigned int i;
> @@ -115,6 +115,8 @@ static int ovl_dentry_revalidate_common(struct dentry *dentry,
> if (!inode)
> return -ECHILD;
>
> + oe = OVL_I_E(inode);
> + lowerstack = ovl_lowerstack(oe);
> upper = ovl_i_dentry_upper(inode);
> if (upper)
> ret = ovl_revalidate_real(upper, flags, weak);
> --
> 2.39.2
>
