Re: [PATCH v4 2/3] tools/nolibc: Add statfs()

[Daniel Palmer]

Hi Thomas,

On Thu, 14 May 2026 at 20:42, Thomas Weißschuh <linux@xxxxxxxxxxxxxx> wrote:
> > +/* Some preprocessor hackery to get struct statfs to
> > + * always be the 64bit one.
> > + */
> > +#define statfs __nolibc_kernel_statfs
> > +#define statfs64 __nolibc_kernel_statfs64
> > +#include <asm/statfs.h>
> > +#undef statfs
> > +#undef statfs64
> > +
> > +#ifdef __NR_statfs64
> > +#define statfs __nolibc_kernel_statfs64
> > +#else
> > +#define statfs __nolibc_kernel_statfs
> > +#endif
>
> This #define can wreak havoc in user code.
> While it would be nice to have statfs() in nolibc,
> I don't see a proper way to work with the current UAPI header.
> Can we do without statfs() for now?

I thought maybe we could look at /proc/mounts but it seems like if
tmpfs is actually ramfs (CONFIG_SHMEM=n) it still shows tmpfs as the
filesystem type.
So we'd be back to square one. Maybe look for tmpfs in /proc/mounts
then try something that ramfs doesn't support like creating a tmp file
and fallocate() on it to see if it's ramfs?

Thanks,

Daniel