[LTP] syscalls/statx13: Add basic test for STATX_WRITE_ATOMIC on regular file

[linuxtestproject.agent@gmail.com]

Hi Gaurav,

On Thu, 17 Sep 2026 16:23:04 +0530, Gaurav Pathak wrote:
> syscalls/statx13: Add basic test for STATX_WRITE_ATOMIC on regular file

> Fixes: #1224

Fixes tags must reference a valid commit SHA in git history. Use
Closes: #1224 or a Link tag to reference an issue.

> -AC_CHECK_MEMBERS([struct statx.stx_mnt_id, struct statx.stx_dio_mem_align],,,[
> +AC_CHECK_MEMBERS([struct statx.stx_mnt_id, struct statx.stx_dio_mem_align, struct statx.stx_atomic_write_unit_max_opt],,,[
>  #define _GNU_SOURCE
>  #include <sys/stat.h>
>  ])

Do not use configure.ac checks to conditionally compile test logic.
Instead, add fallback definitions for STATX_WRITE_ATOMIC,
STATX_ATTR_WRITE_ATOMIC, and stx_atomic_write_* members in
include/lapi/stat.h so the test builds unconditionally.

> /*\
>  * This test validates the STATX_WRITE_ATOMIC feature (introduced in Linux 6.13).
>  * It ensures that supported filesystems (xfs as of now) correctly report their
>  * atomic write limits to user space when queried via statx().
>  *
>  * The test performs the following validations:
>  * - Creates a test file using O_DIRECT (a prerequisite for atomic writes).

Add a blank line before the bulleted list to comply with reST syntax.

> #define _GNU_SOURCE
> #include <sys/param.h>
> #include "tst_test.h"

Include "lapi/stat.h" so statx() and atomic write definitions are
available on older C libraries. <sys/param.h> is unused and should be
removed.

> 	TST_EXP_PASS_SILENT(statx(AT_FDCWD, TESTFILE, 0, STATX_BASIC_STATS | STATX_WRITE_ATOMIC, &buff),
> 			"statx(AT_FDCWD, %s, 0, STATX_WRITE_ATOMIC, &buf)", TESTFILE);
> 
> 	if (!(buff.stx_attributes & STATX_ATTR_WRITE_ATOMIC)) {

TST_EXP_PASS_SILENT() does not abort on error. If statx() fails, execution
proceeds to read uninitialized memory from buff. Add "if (!TST_PASS)
return;" after the call. Also drop the redundant, mismatched format string.

> 	if (buff.stx_atomic_write_unit_max > 0 &&
> 			__builtin_popcount(buff.stx_atomic_write_unit_max) == 1)
> 		tst_res(TPASS, "stx_atomic_write_unit_max(%u) is power of 2",
> 				buff.stx_atomic_write_unit_max);
> 	else
> 		tst_res(TFAIL, "stx_atomic_write_unit_max(%u) is not a power of 2",
> 				buff.stx_atomic_write_unit_max);

Assert that buff.stx_atomic_write_unit_min <=
buff.stx_atomic_write_unit_max. The ordering between min and max is never
checked when stx_atomic_write_unit_max_opt is 0.

> #ifdef HAVE_STRUCT_STATX_STX_ATOMIC_WRITE_UNIT_MAX_OPT
> 	if (buff.stx_atomic_write_unit_max_opt == 0) {
> 		tst_res(TINFO, "stx_atomic_write_unit_max_opt is 0 (no optimized max reported)");
> 	} else {
> 		if (buff.stx_atomic_write_unit_max_opt > buff.stx_atomic_write_unit_max)
> 			tst_res(TFAIL, "stx_atomic_write_unit_max_opt (%u) exceeds max (%u)",
> 					buff.stx_atomic_write_unit_max_opt,
> 					buff.stx_atomic_write_unit_max);
> 
> 		else if (buff.stx_atomic_write_unit_max_opt < buff.stx_atomic_write_unit_min)
> 			tst_res(TFAIL, "stx_atomic_write_unit_max_opt (%u) is less than min (%u)",
> 					buff.stx_atomic_write_unit_max_opt,
> 					buff.stx_atomic_write_unit_min);
> 		else
> 			tst_res(TPASS, "stx_atomic_write_unit_max_opt (%u) is within valid range [%u, %u]",
> 					buff.stx_atomic_write_unit_max_opt,
> 					buff.stx_atomic_write_unit_min,
> 					buff.stx_atomic_write_unit_max);
> 
> 		if (__builtin_popcount(buff.stx_atomic_write_unit_max_opt) != 1)
> 			tst_res(TFAIL, "stx_atomic_write_unit_max_opt (%u) is not a power of 2",
> 					buff.stx_atomic_write_unit_max_opt);
> 	}
> #else
> 	tst_res(TCONF, "stx_atomic_write_unit_max_opt is not defined in struct statx");
> #endif

Do not bury #ifdef feature checks inside test functions. Defining the
members in include/lapi/stat.h removes the need for this guard and TCONF
branch.

> static void setup(void)
> {
> 	char *data_buff = SAFE_MEMALIGN(ALIGNMENT, WRITE_SIZE);
> 
> 	if (strcmp(tst_device->fs_type, "xfs") && strcmp(tst_device->fs_type, "ext4"))
> 		tst_brk(TCONF, "This test only supports ext4 and xfs");
> 
> 	umask(0);
> 	memset(data_buff, '@', WRITE_SIZE);
> 
> 	file_fd =  SAFE_OPEN(TESTFILE, O_RDWR | O_CREAT | O_DIRECT, MODE);
> 	SAFE_WRITE(SAFE_WRITE_ALL, file_fd, data_buff, WRITE_SIZE);
> }

data_buff is allocated with SAFE_MEMALIGN() but never freed. Free
data_buff after SAFE_WRITE(), and move the allocation after the
filesystem check so it is not leaked on tst_brk(). Also remove the extra
space after the '=' assignment.

> static void cleanup(void)
> {
> 	if (file_fd > -1)
> 		SAFE_CLOSE(file_fd);
> }

Use if (file_fd != -1) per LTP conventions.

Also, add an entry for statx13 to runtest/syscalls.

Verdict - Needs revision

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