Merge tag 'ovl-fixes-6.15-rc2' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/overlayfs/vfs

Bring in overlayfs fixes for the current cycle.

* tag 'ovl-fixes-6.15-rc2' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/overlayfs/vfs:
  ovl: remove unused forward declaration
  ovl: don't allow datadir only

Link: https://lore.kernel.org/CAJfpegt-EE4RROKDXA3g5GxAYXQrWcLAL1TfTPK-%3DVmPC7U13g@mail.gmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>

Author: brauner

fs/overlayfs/overlayfs.h

@@ -541,8 +541,6 @@ int ovl_set_metacopy_xattr(struct ovl_fs *ofs, struct dentry *d,
 bool ovl_is_metacopy_dentry(struct dentry *dentry);
 char *ovl_get_redirect_xattr(struct ovl_fs *ofs, const struct path *path, int padding);
 int ovl_ensure_verity_loaded(struct path *path);
-int ovl_get_verity_xattr(struct ovl_fs *ofs, const struct path *path,
-			 u8 *digest_buf, int *buf_length);
 int ovl_validate_verity(struct ovl_fs *ofs,
 			struct path *metapath,
 			struct path *datapath);

fs/overlayfs/super.c

@@ -1138,6 +1138,11 @@ static struct ovl_entry *ovl_get_lowerstack(struct super_block *sb,
 		return ERR_PTR(-EINVAL);
 	}
 
+	if (ctx->nr == ctx->nr_data) {
+		pr_err("at least one non-data lowerdir is required\n");
+		return ERR_PTR(-EINVAL);
+	}
+
 	err = -EINVAL;
 	for (i = 0; i < ctx->nr; i++) {
 		l = &ctx->lower[i];