Linux 6.1 new Direct IO (DIO) "statx" file information example

main.cpp

#include <fcntl.h>    // open, O_CREAT, O_RDWR, AT_FDCWD, AT_STATX_SYNC_AS_STAT
#include <stdio.h>    // printf
#include <sys/stat.h> // statx, STATX_ALL
#include <unistd.h>   // pwrite

#define TMPFILE "test.txt"

int
main()
{
  // Create a temporary file called "test.txt"
  int fd;
  if (-1 == (fd = open(TMPFILE, O_CREAT | O_RDWR, 0666)))
  {
    perror("open");
    return 1;
  }

  // Write 10 bytes to the file
  if (10 != pwrite(fd, "0123456789", 10, 0))
  {
    perror("pwrite");
    return 1;
  }

  // Get the file descriptor
  struct statx statxbuf;
  if (0 != statx(AT_FDCWD, TMPFILE, AT_STATX_SYNC_AS_STAT, STATX_ALL, &statxbuf))
  {
    perror("statx");
    return 1;
  }

  printf("File size: %llu \n", statxbuf.stx_size);
  printf("Direct IO: mem-alignment=%u, offset-alignment=%u \n",
         statxbuf.stx_dio_mem_align,
         statxbuf.stx_dio_offset_align);

  return 0;
}

output.txt

[user@MSI dio-test]$ clang main.cpp -o main
[user@MSI dio-test]$ ./main
File size: 10 
Direct IO: mem-alignment=XXX, offset-alignment=XXX

Kernel commit: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=825cf206ed510c4a1758bef8957e2b039253e2e3