statx requires <sys/stat.h> include file

[wbx-github]

For usage of statx() function you need to include <sys/stat.h>.

When compiling the testsuite with uClibc-ng >= 1.0.57 you get following gcc error:

tests/zfs-tests/cmd/statx.c:58:1: error: conflicting types for 'statx'; have 'int(int, const char *, int, unsigned int, void *)'
58 | statx(int, const char *, int, unsigned int, void *)
| ^~~~~
In file included from /home/wbx/buildroot/br2-zfs/TestZfsUclibc/host/aarch64-buildroot-linux-uclibc/sysroot/usr/include/sys/stat.h:381,
from ./lib/libspl/include/os/linux/sys/stat.h:30,
from /home/wbx/buildroot/br2-zfs/TestZfsUclibc/host/aarch64-buildroot-linux-uclibc/sysroot/usr/include/fcntl.h:37,
from tests/zfs-tests/cmd/statx.c:29:
/home/wbx/buildroot/br2-zfs/TestZfsUclibc/host/aarch64-buildroot-linux-uclibc/sysroot/usr/include/bits/statx.h:98:5: note: previous declaration of 'statx' with type 'int(int, const char * restrict, int, unsigned int, struct statx * restrict)'
98 | int statx (int __dirfd, const char *__restrict __path, int __flags,
| ^~~~~

The reason is that uClibc-ng before 1.0.56 did not expose statx(). With uClibc-ng 1.0.57 there is a mismatch when <fcntl.h> is included, because uClibc-ng has a transient dependency on <sys/stat.h>. Glibc does not include <sys/stat.h>, but <bits/stat.h> in fcntl.h so the error does not happen here, but not the real statx() from glibc is used in this case.

To make both C libraries happy, only define statx() locally, when no statx is recognized via configure and include the correct header.

The test failure was found by the Buildroot project:
https://gitlab.com/jolivain/buildroot/-/jobs/13308829775#L237
See here this thread for the discussion:
https://lists.buildroot.org/pipermail/buildroot/2026-March/797844.html

[behlendorf]

Unfortunately, this seems to break the build with glibc.

  tests/zfs-tests/cmd/statx.c: In function '_statx':
  tests/zfs-tests/cmd/statx.c:67:6: error: the address of 'statx' will always evaluate as 'true' [-Werror=address]
    if (statx)
        ^~~~~
    CC       tests/zfs-tests/cmd/zed_fd_spill-zedlet.o
  cc1: all warnings being treated as errors
  make[4]: *** [Makefile:9121: tests/zfs-tests/cmd/statx.o] Error 1

[wbx-github]

Sorry, I only tested with Buildroot. It seems the patch needs more work for older glibc. Any idea why my patch breaks?

[jolivain]

Hi,

For info, on my side, I tried to workaround this issue with the following patch:
jolivain@d363aaf

I am not sure at the moment it is the best fix for zfs.

It is working in Buildroot in all our cases (Glibc with statx, uclibc < 1.0.57 without statx and 1.0.57 with statx, and musl libc without statx). I tested with:

utils/docker-run support/testing/run-tests \
    -d dl -o output_folder tests.package.test_zfs

Note: Buildroot is not running the zfs tests but is rather checking we can use a zfs partition.

[robn]

Does this build run configure? If so, this is probably best done by checking for statx there, and not building the test binary if it doesn't exist. And then make the test driver SKIP if it can't find the program.

[robn]

Oh maybe never mind, I commented "from the hip" and then saw @jolivain's solution, which is similar but better than what I suggested. I'll have a look later today.

[behlendorf]

@jolivain your fix makes good sense to me. Would you mind opening a PR with it.

[jolivain]

Hi, I rebased my proposed patch, added more info in the commit log, and sent a PR in #18345
Thanks!