When the lower file of a metacopy is inaccessible, -EIO is returned. For users not familiar with overlayfs internals, such as myself, the meaning of this error may not be apparent or easy to determine, since the (metacopy) file is present and open/stat succeed when accessed outside of the overlay. Add a rate-limited warning for orphan metacopy to give users a hint when investigating such errors, as discussed on linux-unionfs[0]. [0]: https://lore.kernel.org/linux-unionfs/CAOQ4uxi23Zsmfb4rCed1n=On0NNA5KZD74jjjeyz+et32sk-gg@xxxxxxxxxxxxxx/ Signed-off-by: Kevin Locke <kevin@xxxxxxxxxxxxxxx> --- Changes since v1: - Use message text similar to suggestion by Amir Goldstein, except that "upper" is removed to avoid confusion if the metacopy is on a middle (i.e. lower-but-not-lowest) layer. fs/overlayfs/namei.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c index f7d4358db637..57cd048ce0af 100644 --- a/fs/overlayfs/namei.c +++ b/fs/overlayfs/namei.c @@ -1000,6 +1000,8 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, * Just make sure a corresponding data dentry has been found. */ if (d.metacopy || (uppermetacopy && !ctr)) { + pr_warn_ratelimited("metacopy with no lower data found - abort lookup (%pd2)\n", + dentry); err = -EIO; goto out_put; } else if (!d.is_dir && upperdentry && !ctr && origin_path) { -- 2.28.0
