On Thu, Feb 06, 2025 at 04:42:42PM +1100, NeilBrown wrote:
> @@ -1700,6 +1702,15 @@ struct dentry *lookup_one_qstr(const struct qstr *name,
> if ((flags & LOOKUP_INTENT_FLAGS) == 0)
> /* ->lookup must have given final answer */
> d_lookup_done(dentry);
> +found:
> + if (d_is_negative(dentry) && !(flags & LOOKUP_CREATE)) {
> + dput(dentry);
> + return ERR_PTR(-ENOENT);
> + }
> + if (d_is_positive(dentry) && (flags & LOOKUP_EXCL)) {
> + dput(dentry);
> + return ERR_PTR(-EEXIST);
> + }
Final dput() on an in-lookup dentry would blow up. What happens if we get
there without LOOKUP_CREATE, but with something else from LOOKUP_INTENT_FLAGS?
That, BTW, is another lovely example of the reasons why making state (in-lookup
in this case, locking elsewhere) transitions dependent upon the function arguments
is a bad idea.
