Re: [PATCH 13/20] ovl: narrow locking in ovl_workdir_cleanup_recurse()

[Amir Goldstein <amir73il@xxxxxxxxx>]

On Fri, Jul 11, 2025 at 1:21 AM NeilBrown <neil@xxxxxxxxxx> wrote:
>
> Only take the dir lock when needed, rather than for the whole loop.
>
> Signed-off-by: NeilBrown <neil@xxxxxxxxxx>
> ---
>  fs/overlayfs/readdir.c | 9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/fs/overlayfs/readdir.c b/fs/overlayfs/readdir.c
> index 3a4bbc178203..b3d44bf56c78 100644
> --- a/fs/overlayfs/readdir.c
> +++ b/fs/overlayfs/readdir.c
> @@ -1122,7 +1122,6 @@ static int ovl_workdir_cleanup_recurse(struct ovl_fs *ofs, const struct path *pa
>         if (err)
>                 goto out;
>
> -       inode_lock_nested(dir, I_MUTEX_PARENT);
>         list_for_each_entry(p, &list, l_node) {
>                 struct dentry *dentry;
>
> @@ -1137,16 +1136,18 @@ static int ovl_workdir_cleanup_recurse(struct ovl_fs *ofs, const struct path *pa
>                         err = -EINVAL;
>                         break;
>                 }
> -               dentry = ovl_lookup_upper(ofs, p->name, path->dentry, p->len);
> +               dentry = ovl_lookup_upper_unlocked(ofs, p->name, path->dentry, p->len);
>                 if (IS_ERR(dentry))
>                         continue;
> -               if (dentry->d_inode)
> +               if (dentry->d_inode) {
> +                       inode_lock_nested(dir, I_MUTEX_PARENT);
>                         err = ovl_workdir_cleanup(ofs, dir, path->mnt, dentry, level);
> +                       inode_unlock(dir);


parent_lock()

Thanks,
Amir.