Re: [PATCH] ltp/fsstress: don't fail on io_uring ENOSYS

[Eryu Guan <guan@eryu.me>]

On Fri, Jan 29, 2021 at 04:10:44PM +0800, Zorro Lang wrote:
> On Thu, Jan 28, 2021 at 03:31:40PM -0600, Eric Sandeen wrote:
> > We might have URING #defined at build time, but be running on a kernel
> > which does not support it.
> > 
> > For that reason, we should not exit with an error if 
> > io_uring_queue_init() fails with ENOSYS. We can just note the lack of
> > support and skip all future io_uring operations.
> > 
> > Signed-off-by: Eric Sandeen <sandeen@redhat.com>
> > ---
> > 
> > diff --git a/ltp/fsstress.c b/ltp/fsstress.c
> > index 22df5e38..73751935 100644
> > --- a/ltp/fsstress.c
> > +++ b/ltp/fsstress.c
> > @@ -35,6 +35,7 @@ io_context_t	io_ctx;
> >  #include <liburing.h>
> >  #define URING_ENTRIES	1
> >  struct io_uring	ring;
> > +bool have_io_uring;			/* to indicate runtime availability */
> >  #endif
> >  #include <sys/syscall.h>
> >  #include <sys/xattr.h>
> > @@ -706,9 +707,15 @@ int main(int argc, char **argv)
> >  			}
> >  #endif
> >  #ifdef URING
> > +			have_io_uring = true;
> > +			/* If ENOSYS, just ignore uring, other errors are fatal. */
> 
> Yes, I thought about if we should do this since rhel8 kernel removed io_uring
> support from kernel, but left userspace liburing. But if we do this for io_uring,
> should we do the same check the others which can be disabled from kernel? Likes: AIO?

io_uring is a relative new interface, and it's quite possible that some
distros don't support it. aio has been there for a long time, and is
very unlikely disabled. If we really need to do the same check for aio,
we could do it in another patch I guess.

Thanks,
Eryu