https://github.com/python/cpython/commit/5a31024da45eb00f5450269cad4481131d77c81f
commit: 5a31024da45eb00f5450269cad4481131d77c81f
branch: main
author: Jeffrey Bosboom <[email protected]>
committer: vstinner <[email protected]>
date: 2025-10-16T13:40:47+02:00
summary:
gh-83714: Check for struct statx.stx_atomic_write_unit_max_opt in configure
(#140185)
stx_atomic_write_unit_max_opt was added in Linux 6.16, but is controlled
by the STATX_WRITE_ATOMIC mask bit added in Linux 6.11. That's safe at
runtime because all kernels clear the reserved space in struct statx and
zero is a valid value for stx_atomic_write_unit_max_opt, and it avoids
allocating another mask bit, which are a limited resource. But it also
means the kernel headers don't provide a way to check whether
stx_atomic_write_unit_max_opt exists, so add a configure check.
files:
M Doc/library/os.rst
M Modules/posixmodule.c
M configure
M configure.ac
M pyconfig.h.in
diff --git a/Doc/library/os.rst b/Doc/library/os.rst
index 1ac87b32badd78..c3ed6a976926fd 100644
--- a/Doc/library/os.rst
+++ b/Doc/library/os.rst
@@ -3496,7 +3496,7 @@ features:
Maximum optimized size for direct I/O with torn-write protection.
.. availability:: Linux >= 4.11 with glibc >= 2.28 and build-time kernel
- userspace API headers >= 6.11.
+ userspace API headers >= 6.16.
.. attribute:: stx_atomic_write_segments_max
diff --git a/Modules/posixmodule.c b/Modules/posixmodule.c
index 5c1c508578a31e..1338be22e18678 100644
--- a/Modules/posixmodule.c
+++ b/Modules/posixmodule.c
@@ -3369,7 +3369,7 @@ static PyMemberDef pystatx_result_members[] = {
MM(stx_atomic_write_segments_max, Py_T_UINT, atomic_write_segments_max,
"maximum iovecs for direct I/O with torn-write protection"),
#endif
-#if 0
+#ifdef HAVE_STRUCT_STATX_STX_ATOMIC_WRITE_UNIT_MAX_OPT
MM(stx_atomic_write_unit_max_opt, Py_T_UINT, atomic_write_unit_max_opt,
"maximum optimized size for direct I/O with torn-write protection"),
#endif
diff --git a/configure b/configure
index 28005cd1924be7..267981250cd7e2 100755
--- a/configure
+++ b/configure
@@ -25133,6 +25133,21 @@ printf "%s\n" "#define HAVE_SIGINFO_T_SI_BAND 1"
>>confdefs.h
fi
+if test "$ac_cv_func_statx" = yes; then
+ # stx_atomic_write_unit_max_opt was added in Linux 6.16, but is controlled by
+ # the STATX_WRITE_ATOMIC mask bit added in Linux 6.11, so having the mask bit
+ # doesn't imply having the member.
+ ac_fn_c_check_member "$LINENO" "struct statx"
"stx_atomic_write_unit_max_opt"
"ac_cv_member_struct_statx_stx_atomic_write_unit_max_opt" "$ac_includes_default"
+if test "x$ac_cv_member_struct_statx_stx_atomic_write_unit_max_opt" = xyes
+then :
+
+printf "%s\n" "#define HAVE_STRUCT_STATX_STX_ATOMIC_WRITE_UNIT_MAX_OPT 1"
>>confdefs.h
+
+
+fi
+
+fi
+
{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for time.h that defines
altzone" >&5
printf %s "checking for time.h that defines altzone... " >&6; }
if test ${ac_cv_header_time_altzone+y}
diff --git a/configure.ac b/configure.ac
index d20f6f8c40abeb..382591952ef68f 100644
--- a/configure.ac
+++ b/configure.ac
@@ -5819,6 +5819,13 @@ AC_CHECK_MEMBERS([struct passwd.pw_gecos, struct
passwd.pw_passwd], [], [], [[
# Issue #21085: In Cygwin, siginfo_t does not have si_band field.
AC_CHECK_MEMBERS([siginfo_t.si_band], [], [], [[@%:@include <signal.h>]])
+if test "$ac_cv_func_statx" = yes; then
+ # stx_atomic_write_unit_max_opt was added in Linux 6.16, but is controlled by
+ # the STATX_WRITE_ATOMIC mask bit added in Linux 6.11, so having the mask bit
+ # doesn't imply having the member.
+ AC_CHECK_MEMBERS([struct statx.stx_atomic_write_unit_max_opt])
+fi
+
AC_CACHE_CHECK([for time.h that defines altzone], [ac_cv_header_time_altzone],
[
AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[@%:@include <time.h>]], [[return
altzone;]])],
[ac_cv_header_time_altzone=yes],
diff --git a/pyconfig.h.in b/pyconfig.h.in
index 611408d88f05b5..092f96e7152e11 100644
--- a/pyconfig.h.in
+++ b/pyconfig.h.in
@@ -1330,6 +1330,10 @@
/* Define to 1 if 'pw_passwd' is a member of 'struct passwd'. */
#undef HAVE_STRUCT_PASSWD_PW_PASSWD
+/* Define to 1 if 'stx_atomic_write_unit_max_opt' is a member of 'struct
+ statx'. */
+#undef HAVE_STRUCT_STATX_STX_ATOMIC_WRITE_UNIT_MAX_OPT
+
/* Define to 1 if 'st_birthtime' is a member of 'struct stat'. */
#undef HAVE_STRUCT_STAT_ST_BIRTHTIME
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