src/unwritten_mmap.c

   1 #include <stdio.h>
   2 #include <stdlib.h>
   3 #include <unistd.h>
   4 #include <fcntl.h>
   5 #include <xfs/xfs.h>
   6 #include <sys/mman.h>
   7
   8 /*
   9  * mmap a preallocated file and write to a set of offsets
  10  * in it. We'll check to see if the underlying extents are
  11  * converted correctly on writeback.
  12  */
  13 int main(int argc, char **argv) {
  14         unsigned long long o;
  15         int fd, i;
  16         struct xfs_flock64 space;
  17         unsigned char *buf;
  18
  19         if(argc < 3) {
  20                 fprintf(stderr, "%s <count> <file [file...]>\n", argv[0]);
  21                 exit(1);
  22         }
  23
  24         errno = 0;
  25         o = strtoull(argv[1], NULL, 0);
  26         if (errno) {
  27                 perror("strtoull");
  28                 exit(errno);
  29         }
  30
  31         for(i = 2; i < argc; i++) {
  32                 unlink(argv[i]);
  33                 fd = open(argv[i], O_RDWR|O_CREAT|O_LARGEFILE, 0666);
  34                 if(fd < 0) {
  35                         perror("open");
  36                         exit(2);
  37                 }
  38
  39                 if(ftruncate64(fd, o) < 0) {
  40                         perror("ftruncate64");
  41                         exit(3);
  42                 }
  43
  44                 space.l_whence = SEEK_SET;
  45                 space.l_start = 0;
  46                 space.l_len = o;
  47
  48                 if(ioctl(fd, XFS_IOC_RESVSP64, &space)) {
  49                         perror("ioctl()");
  50                         exit(4);
  51                 }
  52
  53                 buf = mmap(NULL, (int)o, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
  54                 if(buf == MAP_FAILED) {
  55                         perror("mmap()");
  56                         exit(5);
  57                 } else {
  58                         buf[o-1] = 0;
  59                         buf[o/2] = 0;
  60                         buf[0] = 0;
  61                         munmap(buf, o);
  62                 }
  63
  64                 fsync(fd);
  65                 if(close(fd) == -1) {
  66                         perror("close");
  67                         exit(6);
  68                 }
  69         }
  70         exit(0);
  71 }