On Wed, Oct 09, 2019 at 08:29:11AM -0700, Christoph Hellwig wrote:
> On Wed, Oct 09, 2019 at 04:21:27PM +0100, Al Viro wrote:
> > What we need to do is to turn fs_parameter_type into a pointer
> > to function. With fs_param_is_bool et.al. becoming instances
> > of such, and fs_parse() switch from hell turning into
> > err = p->type(p, param, result);
> >
> > That won't affect the existing macros or any filesystem code.
> > If some filesystem wants to have helpers of its own - more
> > power to it, just use __fsparam(my_bloody_helper, "foo", Opt_foo, 0)
> > and be done with that.
>
> Actually, while we could keep the old macros around at least
> temporarily for existing users I think killing them actually would
> improve the file systems as well.
>
> This:
>
> static const struct fs_parameter_spec afs_param_specs[] = {
> { "autocell", Opt_autocell, fs_parse_flag },
> { "dyn", Opt_dyn, fs_parse_flag },
> { "flock", Opt_flock, fs_parse_enum },
> { "source", Opt_source, fs_parse_string },
> {}
> };
>
>
> is a lot more obvious than:
>
> static const struct fs_parameter_spec afs_param_specs[] = {
> fsparam_flag ("autocell", Opt_autocell),
> fsparam_flag ("dyn", Opt_dyn),
> fsparam_enum ("flock", Opt_flock),
> fsparam_string("source", Opt_source),
> {}
> };
Except that I want to be able to have something like
- fsparam_enum ("errors", Opt_errors),
+ fsparam_enum ("errors", Opt_errors, gfs2_param_errors),
with
+static const struct fs_parameter_enum gfs2_param_errors[] = {
+ {"withdraw", Opt_errors_withdraw },
+ {"panic", Opt_errors_panic },
+ {}
+};
instead of having them all squashed into one array, as in
-static const struct fs_parameter_enum gfs2_param_enums[] = {
- { Opt_quota, "off", Opt_quota_off },
- { Opt_quota, "account", Opt_quota_account },
- { Opt_quota, "on", Opt_quota_on },
- { Opt_data, "writeback", Opt_data_writeback },
- { Opt_data, "ordered", Opt_data_ordered },
- { Opt_errors, "withdraw", Opt_errors_withdraw },
- { Opt_errors, "panic", Opt_errors_panic },
...
const struct fs_parameter_description gfs2_fs_parameters = {
.name = "gfs2",
.specs = gfs2_param_specs,
- .enums = gfs2_param_enums,
};
IOW, I want to kill ->enums thing. And ->name is also trivial
to kill, at which point we are left with just what used to be
->specs.
Another thing is, struct fs_parameter_enum becomes pretty
much identical to struct constant_table and can be folded into it.
I have some experiments in that direction (very incomplete right
now) in #work.mount-parser-later; next cycle fodder, I'm afraid.
Another thing is, consider something like "it's an
integer in range from 2 to 36". Fairly useful in many cases,
and we could do helpers for that. Except that they need a pointer
to helper-private data (the limits)...
These macros somewhat isolate the filesystems until the
things settle down. And one needs examples of conversions to
see what's missing - inventing a grand scheme out of thin air
doesn't work...
