On Wed, Jul 16, 2025 at 2:47 AM NeilBrown <neil@xxxxxxxxxx> wrote:
>
> In ovl_workdir_create() don't hold the dir lock for the whole time, but
> only take it when needed.
>
> It now gets taken separately for ovl_workdir_cleanup(). A subsequent
> patch will move the locking into that function.
>
> Signed-off-by: NeilBrown <neil@xxxxxxxxxx>
Reviewed-by: Amir Goldstein <amir73il@xxxxxxxxx>
> ---
> fs/overlayfs/super.c | 25 ++++++++++++++-----------
> 1 file changed, 14 insertions(+), 11 deletions(-)
>
> diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
> index 2e6b25bde83f..cb2551a155d8 100644
> --- a/fs/overlayfs/super.c
> +++ b/fs/overlayfs/super.c
> @@ -299,8 +299,8 @@ static struct dentry *ovl_workdir_create(struct ovl_fs *ofs,
> int err;
> bool retried = false;
>
> - inode_lock_nested(dir, I_MUTEX_PARENT);
> retry:
> + inode_lock_nested(dir, I_MUTEX_PARENT);
> work = ovl_lookup_upper(ofs, name, ofs->workbasedir, strlen(name));
>
> if (!IS_ERR(work)) {
> @@ -311,23 +311,28 @@ static struct dentry *ovl_workdir_create(struct ovl_fs *ofs,
>
> if (work->d_inode) {
> err = -EEXIST;
> + inode_unlock(dir);
> if (retried)
> goto out_dput;
>
> if (persist)
> - goto out_unlock;
> + return work;
>
> retried = true;
> - err = ovl_workdir_cleanup(ofs, dir, mnt, work, 0);
> - dput(work);
> - if (err == -EINVAL) {
> - work = ERR_PTR(err);
> - goto out_unlock;
> + err = ovl_parent_lock(ofs->workbasedir, work);
> + if (!err) {
> + err = ovl_workdir_cleanup(ofs, dir, mnt, work, 0);
> + ovl_parent_unlock(ofs->workbasedir);
> }
> + dput(work);
> + if (err == -EINVAL)
> + return ERR_PTR(err);
> +
> goto retry;
> }
>
> work = ovl_do_mkdir(ofs, dir, work, attr.ia_mode);
> + inode_unlock(dir);
> err = PTR_ERR(work);
> if (IS_ERR(work))
> goto out_err;
> @@ -365,11 +370,10 @@ static struct dentry *ovl_workdir_create(struct ovl_fs *ofs,
> if (err)
> goto out_dput;
> } else {
> + inode_unlock(dir);
> err = PTR_ERR(work);
> goto out_err;
> }
> -out_unlock:
> - inode_unlock(dir);
> return work;
>
> out_dput:
> @@ -377,8 +381,7 @@ static struct dentry *ovl_workdir_create(struct ovl_fs *ofs,
> out_err:
> pr_warn("failed to create directory %s/%s (errno: %i); mounting read-only\n",
> ofs->config.workdir, name, -err);
> - work = NULL;
> - goto out_unlock;
> + return NULL;
> }
>
> static int ovl_check_namelen(const struct path *path, struct ovl_fs *ofs,
> --
> 2.49.0
>
