OpenZFS 2.3.0-rc3 & UCLIBC. Crash while compiling. MS_RDONLY = 1

[jlsalvador]

Hi again,

I’m currently outside with very limited internet access and no computer, only a phone. Please excuse the brief explanation and lack of proper debugging.

The compilation crash for uClibc with OpenZFS 2.3.0-rc3 is as follows (note that it works correctly with glibc and musl):

In file included from tests/zfs-tests/cmd/getversion.c:22:
/tmp/tmp.s4lnjcKpqa/TestZfsUclibc/host/x86_64-buildroot-linux-uclibc/sysroot/usr/include/sys/mount.h:35:3: error: expected identifier before numeric constant
   35 |   MS_RDONLY = 1,                /* Mount read-only.  */
      |   ^~~~~~~~~
  CC       tests/zfs-tests/cmd/idmap_util.o
make[4]: *** [Makefile:8906: tests/zfs-tests/cmd/getversion.o] Error 1
make[4]: *** Waiting for unfinished jobs....                                  make[3]: *** [Makefile:12578: all-recursive] Error 1                          make[2]: *** [Makefile:4751: all] Error 2                                     make[1]: *** [package/pkg-generic.mk:289: /tmp/tmp.s4lnjcKpqa/TestZfsUclibc/build/zfs-2.3.0-rc3/.stamp_built] Error 2
make: *** [Makefile:23: _all] Error 2
E                                                                             ======================================================================
ERROR: test_run (tests.package.test_zfs.TestZfsUclibc.test_run)
----------------------------------------------------------------------        Traceback (most recent call last):                                              File "/home/jlsalvador/src/simplek8s-buildroot/buildroot/support/testing/infra/basetest.py", line 74, in setUp                                                self.b.build()                                                              File "/home/jlsalvador/src/simplek8s-buildroot/buildroot/support/testing/infra/builder.py", line 105, in build
    raise SystemError("Build failed")                                         SystemError: Build failed

----------------------------------------------------------------------        Ran 1 test in 471.419s                                                        
FAILED (errors=1)

System information

Type	Version/Name
Distribution Name	buildroot
Distribution Version	main
Kernel Version	5.15.35
Architecture	x86-64
OpenZFS Version	2.3.0-rc3

Describe the problem you're observing

Describe how to reproduce the problem

Include any warning/errors/backtraces from the system logs

[jlsalvador]

AFK for ~48h. I will debug it later.

[robn]

Just from proximity, I wonder if #15925 broke this? @thesamesam?

[thesamesam]

I'll take a look, thanks for the ping. I know what the class of problem is (unfortunate clashes with linux-headers vs libc headers), but the specifics need checking.

@jlsalvador Gentoo doesn't support uclibc anymore so it's not easy for me to quickly get an env setup. Do you have any recommendations for how I can?

[jlsalvador]

I'll take a look, thanks for the ping. I know what the class of problem is (unfortunate clashes with linux-headers vs libc headers), but the specifics need checking.

@jlsalvador Gentoo doesn't support uclibc anymore so it's not easy for me to quickly get an env setup. Do you have any recommendations for how I can?

git clone https://gitlab.com/buildroot.org/buildroot.git

cd buildroot

./support/testing/run-tests -d $(pwd)/dl -o $(mktemp -d) -s tests.package.test_zfs.TestZfsUclibc.test_run

patch to openzfs-2.3.0-rc3:
https://gist.github.com/jlsalvador/9b6bd33a569c049438831f38b4054744

[jlsalvador]

Just from proximity, I wonder if #15925 broke this? @thesamesam?

It compiles when the commit e12d761 is reverted.

[jlsalvador]

tests/zfs-tests/cmd/getversion.c needs as fallback:

#ifdef _KERNEL
#include <sys/fcntl.h>
#else
#include <fcntl.h>
#endif

[thesamesam]

Thanks, that LGTM (and it's the issue I thought I'd seen in that PR but then couldn't reproduce at all later). Want to submit it or should I?

[jlsalvador]

Thanks, that LGTM (and it's the issue I thought I'd seen in that PR but then couldn't reproduce at all later). Want to submit it or should I?

I won't be able to make a proper commit for about 24 hours, but I'm happy if you want to commit a proper solution before then. 👍

[jlsalvador]

tests/zfs-tests/cmd/getversion.c needs as fallback:

#ifdef _KERNEL
#include <sys/fcntl.h>
#else
#include <fcntl.h>
#endif

This does not fix the issue.

[jlsalvador]

Moving fcntl.h before linux/fs.h fix the problem.
Debugging and testing for others toolchains (glibc, musl and uclibc) before the PR.

[jlsalvador]

Just moving fcntl.h before linux/fs.h is good enough for uClibc.
@thesamesam can you test my PR (#16741) in your environment?