Re: [EXPERIMENT] new mount API verbose errors from userspace

["Aurélien Aptel" <aaptel@suse.com>]

ronnie sahlberg <ronniesahlberg@gmail.com> writes:
> I like this, this is very nice.
> But, as you touch upon, it requires we know in mount.c what type each
> argument is.
> Which is problematic because the list of mount arguments in cifs.ko
> has a fair amount of crunch
> and I think it would be unworkable to keep cifs-utils and cifs.ko in
> lockstep for every release where
> we modify a mount argument.

We could do some basic pattern matching: like if has no '=', assume
boolean flag. If value only made of number, assume int. String for
everything else.

But this might fail on numbers which are actually string
(e.g. password=123456).

> What I think we should have is a ioctl(),  system-call,
> /proc/fs/cifs/options,  where we can query the kernel/file-system
> module
> for "give me a list of all recognized mount options and their type"
> i.e. basically a way to fetch the "struct fs_parameter_spec" to userspace.
>
> This is probably something that would not be specific to cifs, but
> would apply to all filesystem modules.

That sounds like a good idea yes. I wonder if David Howells has
considered this.

We can already sort-of do this actually. We can have a special boolean
option "help" which on the kernel side would log the list of
options&types in the fs_context log (as "i" (info) messages).

Cheers,
-- 
Aurélien Aptel / SUSE Labs Samba Team
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