On Mon, Nov 11, 2024 at 08:42:26AM -0500, Jeff Layton wrote:
> On Mon, 2024-11-11 at 10:17 +0100, Christian Brauner wrote:
> > On Thu, 07 Nov 2024 16:00:05 -0500, Jeff Layton wrote:
> > > Meta has some internal logging that scrapes /proc/self/mountinfo today.
> > > I'd like to convert it to use listmount()/statmount(), so we can do a
> > > better job of monitoring with containers. We're missing some fields
> > > though. This patchset adds them.
> > >
> > >
> >
> > I know Karel has been wanting this for libmount as well. Thanks for
> > doing this! It would be nice if you could also add some selftests!
> >
>
> (cc'ing Karel)
>
> Thanks. We may need to tweak this a bit, based on Miklos' comments
> about how empty strings are handled now, but it shouldn't be too big a
> change.
>
> I actually have a related question about libmount: glibc doesn't
> currently provide syscall wrappers for statmount() and listmount().
I think it'll be a bit until glibc exposes those system calls because I
think they are special-purpose in a lot of ways. But also because glibc
usually takes a while to add new system call wrappers.
> Would it make sense to have libmount provide those? We could copy the
I think libmount may not necessarily provide direct syscall wrappers but
will expose new api functionality. This is at least what I gather from
all the discussions on util-linux.
> wrappers in tools/testing/selftests/filesystems/statmount/statmount.h
> to libmount.h.
>
> It's error-prone and a pain to roll these yourself, and that would make
As with most system calls.
> things simpler until someone is ready to do something for glibc.
>
> Another idea might be to start a new userland header file that is just
> a collection of static inline wrappers for syscalls that aren't
> packaged in glibc.e.g. pidfd_open also doesn't have glibc bindings, so
> we could add that there too.
Oh? What glibc version are you on? pidfd_open() et al should all have
glibc wrappers afaik. It just always takes a while:
> cat /usr/include/x86_64-linux-gnu/sys/pidfd.h | grep pidfd
extern int pidfd_open (__pid_t __pid, unsigned int __flags) __THROW;
extern int pidfd_getfd (int __pidfd, int __targetfd,
extern int pidfd_send_signal (int __pidfd, int __sig, siginfo_t *__info,
extern pid_t pidfd_getpid (int __fd) __THROW;
