Re: [PATCH RFC 1/3] fs: introduce helper d_path_fast()

Eric W. Biederman
2021-05-10T16:16:19Z

Al Viro <viro@zeniv.linux.org.uk> writes:
>
> Another thing that keeps bugging me about prepend_path() is the
> set of return values. I mean, 0/1/2/3/-ENAMETOOLONG, and all
> except 0 are unlikely? Might as well make that 0/1/2/3/-1, if
> not an outright 0/1/2/3/4. And prepend() could return bool, while
> we are at it (true - success, false - overflow)...

I remember seeing that the different callers of prepend_path treated
those different cases differently.

But now that I look again the return value 3 (escaped) gets lumped
together with 2(detached).

On second look it appears that the two patterns that we actually have
are basically:

char *__d_path(const struct path *path,
const struct path *root,
char *buf, int buflen)
{
error = prepend_path(path, root, &res, &buflen);

if (error < 0)
return ERR_PTR(error);
if (error > 0)
return NULL;
return res;
}

char *d_absolute_path(const struct path *path,
char *buf, int buflen)
{
error = prepend_path(path, &root, &res, &buflen);

if (error > 1)
error = -EINVAL;
if (error < 0)
return ERR_PTR(error);
return res;
}

With d_absolute_path deciding that return value 1 absolute is not an
error.

That does look like there is plenty of room to refactor and make things
clearer.

Eric