[LTP] [PATCH] configure.ac: Fix redefinition of mount_attr by checking sys/mount.h

[Marcos Paulo de Souza]

On Mon, Sep 26, 2022 at 09:26:33PM +0200, Petr Vorel wrote:
> Hi Marcos,
> 
> > mount_setattr and mount_attr are defined in sys/mount.h.
> 
> > Signed-off-by: Marcos Paulo de Souza <mpdesouza@suse.com>
> > ---
> >  Tested on openSUSE Tumbleweed
> 
> >  configure.ac | 1 +
> >  1 file changed, 1 insertion(+)
> 
> > diff --git a/configure.ac b/configure.ac
> > index 1deeffc0c..0e9895415 100644
> > --- a/configure.ac
> > +++ b/configure.ac
> > @@ -71,6 +71,7 @@ AC_CHECK_HEADERS_ONCE([ \
> >      sys/epoll.h \
> >      sys/fanotify.h \
> >      sys/inotify.h \
> > +    sys/mount.h \
> 
> Well, we don't add check for this, as sys/mount.h has been here since "ever", so
> it'd just make configure little bit slower for no gain.
> 
> But you'd have to use somewhere compiler macro #ifdef HAVE_SYS_MOUNT_H, as this
> macro is generated by configure script. Adding header to the list does nothing.

It wasn't needed in my case, let me explain better below.

> 
> You obviously wanted to fix something, could you post the problem you're trying
> to solve + steps you did to ML?

I was seeing redefinition problems:

In file included from fsconfig01.c:9:
../../../../include/lapi/fsmount.h:55:8: error: redefinition of 'struct mount_attr'
   55 | struct mount_attr {
      |        ^~~~~~~~~~
In file included from /usr/include/sys/mount.h:32,
                 from ../../../../include/lapi/fsmount.h:14:
/usr/include/linux/mount.h:129:8: note: originally defined here
  129 | struct mount_attr {
      |        ^~~~~~~~~~
../../../../include/lapi/fsmount.h:110:19: error: conflicting types for 'mount_setattr'; have 'int(int,  const char *, unsigned int,  struct mount_attr *, size_t)' {aka 'int(int,  const char *, unsigned int,  struct mount_attr *, long unsigned int)'}
  110 | static inline int mount_setattr(int dirfd, const char *from_pathname, unsigned int flags,
      |                   ^~~~~~~~~~~~~
In file included from fsconfig02.c:8:
../../../../include/lapi/fsmount.h:55:8: error: redefinition of 'struct mount_attr'
   55 | struct mount_attr {
      |        ^~~~~~~~~~
/usr/include/sys/mount.h:316:12: note: previous declaration of 'mount_setattr' with type 'int(int,  const char *, unsigned int,  struct mount_attr *, size_t)' {aka 'int(int,  const char *, unsigned int,  struct mount_attr *, long unsigned int)'}
  316 | extern int mount_setattr (int __dfd, const char *__path, unsigned int __flags,
      |            ^~~~~~~~~~~~~
In file included from /usr/include/sys/mount.h:32,
                 from ../../../../include/lapi/fsmount.h:14:
/usr/include/linux/mount.h:129:8: note: originally defined here
  129 | struct mount_attr {
      |        ^~~~~~~~~~
../../../../include/lapi/fsmount.h:110:19: error: conflicting types for 'mount_setattr'; have 'int(int,  const char *, unsigned int,  struct mount_attr *, size_t)' {aka 'int(int,  const char *, unsigned int,  struct mount_attr *, long unsigned int)'}
  110 | static inline int mount_setattr(int dirfd, const char *from_pathname, unsigned int flags,
      |                   ^~~~~~~~~~~~~
/usr/include/sys/mount.h:316:12: note: previous declaration of 'mount_setattr' with type 'int(int,  const char *, unsigned int,  struct mount_attr *, size_t)' {aka 'int(int,  const char *, unsigned int,  struct mount_attr *, long unsigned int)'}
  316 | extern int mount_setattr (int __dfd, const char *__path, unsigned int __flags,
      |            ^~~~~~~~~~~~~
make[4]: *** [../../../../include/mk/rules.mk:45: fsconfig01] Error 1
make[4]: *** Waiting for unfinished jobs....
make[4]: *** [../../../../include/mk/rules.mk:45: fsconfig02] Error 1
make[3]: *** [../../../include/mk/generic_trunk_target.inc:108: all] Error 2
make[2]: *** [../../include/mk/generic_trunk_target.inc:108: all] Error 2
make[1]: *** [../include/mk/generic_trunk_target.inc:108: all] Error 2
make[1]: Leaving directory '/home/mpdesouza/git/ltp/testcases'
make: *** [Makefile:106: testcases-all] Error 2

In my TW system I found that the struct mount_attr was being defined in
sys/mount.h. Checking include/lapi/fsmount.h I found some ifdefs:

...
#ifndef HAVE_STRUCT_MOUNT_ATTR
/*
 * mount_setattr()
 */
struct mount_attr {
        uint64_t attr_set;
        uint64_t attr_clr;
        uint64_t propagation;
        uint64_t userns_fd;
};
#endif
...

#ifndef HAVE_MOUNT_SETATTR
static inline int mount_setattr(int dirfd, const char *from_pathname, unsigned int flags,
                                struct mount_attr *attr, size_t size)
{
        return tst_syscall(__NR_mount_setattr, dirfd, from_pathname, flags,
                           attr, size);
}
#endif /* HAVE_MOUNT_SETATTR */

So, only adding the sys/mount.h entry to the headers list is enough to make
autoconf to find that sys/mount.h defines the same struct and function, fixing
the issue.

> 
> BTW I have no problem to build locally on the latest Tumbleweed. Also LTP
> package build for Tumbleweed is also fine:
> https://build.opensuse.org/package/binaries/benchmark:ltp:devel/ltp/openSUSE_Factory
> https://build.opensuse.org/package/binaries/benchmark:ltp:devel/ltp/openSUSE_Tumbleweed

Interesting... so is there anything wrong with my setup? Am I missing something?

> 
> Kind regards,
> Petr