Christian Brauner [off-list ref] writes:

On Mon, Mar 11, 2024 at 03:39:39PM +0100, Miklos Szeredi wrote:

quoted

On Mon, 11 Mar 2024 at 14:25, Christian Brauner [off-list ref] wrote:

quoted

Yeah, so with that I do agree. But have you read my reply to the other
thread? I'd like to hear your thoughs on that. The problem is that
mount(8) currently does:

fsconfig(3, FSCONFIG_SET_FLAG, "usrjquota", NULL, 0) = -1 EINVAL (Invalid argument)

for both -o usrjquota and -o usrjquota=

For "-o usrjquota" this seems right.

For "-o usrjquota=" it doesn't.  Flags should never have that "=", so
this seems buggy in more than one ways.

quoted

So we need a clear contract with userspace or the in-kernel solution
proposed here. I see the following options:

(1) Userspace must know that mount options such as "usrjquota" that can
    have no value must be specified as "usrjquota=" when passed to
    mount(8). This in turn means we need to tell Karel to update
    mount(8) to recognize this and infer from "usrjquota=" that it must
    be passed as FSCONFIG_SET_STRING.

Yes, this is what I'm thinking.  Of course this only works if there
are no backward compatibility issues, if "-o usrjquota" worked in the
past and some systems out there relied on this, then this is not
sufficient.

Ok, I spoke to Karel and filed:

https://github.com/util-linux/util-linux/issues/2837

So this should get sorted soon.

OK, so I if I understand it correctly I can drop all these changes as
there's nothing else to be done from the kernel, right?

(I'll still send out a patch to move the fsparam_string_empty() helper to
a generic header.)

And thanks everyone for your reviews.

Cheers,
-- 
Luís