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

[linuxtestproject.agent@gmail.com]

Hi Gaurav,

On Thu Sep 17 16:23:04 2026 +0530, Gaurav Pathak <gaurav.pathak@suse.com> wrote:
> syscalls/statx13: Add basic test for STATX_WRITE_ATOMIC on regular file

> Fixes: #1224

Fixes: must reference a valid commit SHA in local git history. If
referencing a GitHub issue, use Closes: #1224 instead.

> diff --git a/testcases/kernel/syscalls/statx/.gitignore b/testcases/kernel/syscalls/statx/.gitignore
> index f6a423eed..e601a46a3 100644
> --- a/testcases/kernel/syscalls/statx/.gitignore
> +++ b/testcases/kernel/syscalls/statx/.gitignore
> @@ -10,3 +10,4 @@
>  /statx10
>  /statx11
>  /statx12
> +/statx13

The new test must also be added to runtest/syscalls.

> -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>
>  ])

Compile-time checks in configure.ac may only enable fallback API
definitions in include/lapi/. Fallback definitions for STATX_WRITE_ATOMIC,
STATX_ATTR_WRITE_ATOMIC, and the atomic write struct statx fields belong
in include/lapi/stat.h so the test builds on distributions with older libc
headers.

> + * The test performs the following validations:
> + * - Creates a test file using O_DIRECT (a prerequisite for atomic writes).
> + * - Calls statx() with the STATX_WRITE_ATOMIC mask to retrieve the limits.
> + * - Verifies that stx_atomic_write_unit_min, stx_atomic_write_unit_max, and
> + *    stx_atomic_write_unit_max_opt are logically consistent (e.g., max_opt is
> + *    within the min and max bounds).
> + * - Ensures all reported atomic write unit sizes are valid powers of two.

Add a blank line before the bulleted list. Reference the syscall as
:manpage:`statx(2)` and align the continuation indentation on line 15.
Also update the doc comment regarding supported filesystems since ext4 is
tested as well.

> +#define _GNU_SOURCE
> +#include <sys/param.h>
> +#include "tst_test.h"
> +
> +#define MNTPOINT "mnt_point"
> +#define TESTFILE MNTPOINT"/testfile"

Drop unused <sys/param.h> and include "lapi/stat.h". Add a space between
concatenated string literals: MNTPOINT "/testfile".

> +static void verify_statx(void)
> +{
> +	struct statx buff;

Tested syscall struct arguments must not be allocated on the stack.
Declare a static pointer and allocate it via .bufs in struct tst_test.

> +#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 {
[...]
> +#else
> +	tst_res(TCONF, "stx_atomic_write_unit_max_opt is not defined in struct statx");
> +#endif

Compile-time feature guards must not be placed inside function bodies.
Provide fallback definitions in include/lapi/stat.h instead.

> +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 never freed, leaking memory. Free it after SAFE_WRITE(), and
perform the allocation after the filesystem check to avoid leaking on
tst_brk().

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

Use if (file_fd != -1) to check file descriptor validity. Also, file_fd is
kept open across test iterations but verify_statx() only accesses TESTFILE
by path; close file_fd in setup() after writing if fd-based statx is not
tested.

Verdict - Needs revision

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