src/t_stripealign.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * t_stripealign.c
   4  * Print whether the file start block is stripe-aligned.
   5  * Copyright (c) 2010 Eric Sandeen <sandeen@sandeen.net>
   6  */
   7 #include <unistd.h>
   8 #include <stdlib.h>
   9 #include <sys/types.h>
  10 #include <sys/vfs.h>
  11 #include <fcntl.h>
  12 #include <stdio.h>
  13 #include <sys/ioctl.h>
  14 #include <linux/fiemap.h>
  15 #include <linux/fs.h>
  16
  17 #ifndef FIEMAP_EXTENT_SHARED
  18 # define FIEMAP_EXTENT_SHARED   0x00002000
  19 #endif
  20
  21 #define FIEMAP_EXTENT_ACCEPTABLE        (FIEMAP_EXTENT_LAST | \
  22                 FIEMAP_EXTENT_DATA_ENCRYPTED | FIEMAP_EXTENT_ENCODED | \
  23                 FIEMAP_EXTENT_UNWRITTEN | FIEMAP_EXTENT_MERGED | \
  24                 FIEMAP_EXTENT_SHARED)
  25
  26 /*
  27  * If only filename given, print first block.
  28  *
  29  * If filename & sunit (in blocks) given, print whether we are well-aligned
  30  */
  31
  32 int main(int argc, char ** argv)
  33 {
  34         struct statfs           sb;
  35         struct fiemap           *fie;
  36         struct fiemap_extent    *fe;
  37         int                     fd;
  38         int                     ret;
  39         int                     sunit = 0;      /* in blocks */
  40         char                    *filename;
  41         unsigned long long      block;
  42
  43         if (argc < 3) {
  44                 printf("Usage: %s <filename> <sunit in blocks>\n", argv[0]);
  45                 return 1;
  46         }
  47
  48         filename = argv[1];
  49         sunit = atoi(argv[2]);
  50
  51         fd = open(filename, O_RDONLY);
  52         if (fd < 0) {
  53                 perror("can't open file\n");
  54                 return 1;
  55         }
  56
  57         ret = fstatfs(fd, &sb);
  58         if (ret) {
  59                 perror(filename);
  60                 close(fd);
  61                 return 1;
  62         }
  63
  64         fie = calloc(1, sizeof(struct fiemap) + sizeof(struct fiemap_extent));
  65         if (!fie) {
  66                 close(fd);
  67                 perror("malloc");
  68                 return 1;
  69         }
  70         fie->fm_length = 1;
  71         fie->fm_flags = FIEMAP_FLAG_SYNC;
  72         fie->fm_extent_count = 1;
  73
  74         ret = ioctl(fd, FS_IOC_FIEMAP, fie);
  75         if (ret < 0) {
  76                 unsigned int    bmap = 0;
  77
  78                 ret = ioctl(fd, FIBMAP, &bmap);
  79                 if (ret <= 0) {
  80                         if (ret < 0)
  81                                 perror("fibmap");
  82                         else
  83                                 fprintf(stderr, "fibmap returned no result\n");
  84                         free(fie);
  85                         close(fd);
  86                         return 1;
  87                 }
  88                 block = bmap;
  89                 goto check;
  90         }
  91
  92
  93         if (fie->fm_mapped_extents != 1) {
  94                 printf("%s: no extents?\n", filename);
  95                 free(fie);
  96                 close(fd);
  97                 return 1;
  98         }
  99         fe = &fie->fm_extents[0];
 100         if (fe->fe_flags & ~FIEMAP_EXTENT_ACCEPTABLE) {
 101                 printf("%s: bad flags 0x%x\n", filename, fe->fe_flags);
 102                 free(fie);
 103                 close(fd);
 104                 return 1;
 105         }
 106
 107         block = fie->fm_extents[0].fe_physical / sb.f_bsize;
 108 check:
 109         if (block % sunit) {
 110                 printf("%s: Start block %llu not multiple of sunit %u\n",
 111                         filename, block, sunit);
 112                 return 1;
 113         } else
 114                 printf("%s: well-aligned\n", filename);
 115         free(fie);
 116         close(fd);
 117
 118         return 0;
 119 }