mount_root.c

   1 /*
   2  * Copyright (C) 2014 John Crispin <blogic@openwrt.org>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU Lesser General Public License version 2.1
   6  * as published by the Free Software Foundation
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11  * GNU General Public License for more details.
  12  */
  13
  14 #include <sys/mount.h>
  15 #include <stdio.h>
  16 #include <stdlib.h>
  17
  18 #include "libfstools/libfstools.h"
  19 #include "libfstools/volume.h"
  20
  21 /*
  22  * Called in the early (PREINIT) stage, when we immediately need some writable
  23  * filesystem.
  24  */
  25 static int
  26 start(int argc, char *argv[1])
  27 {
  28         struct volume *v = volume_find("rootfs_data");
  29
  30         if (!getenv("PREINIT"))
  31                 return -1;
  32
  33         if (!v) {
  34                 v = volume_find("rootfs");
  35                 volume_init(v);
  36                 fprintf(stderr, "mounting /dev/root\n");
  37                 mount("/dev/root", "/", NULL, MS_NOATIME | MS_REMOUNT, 0);
  38                 return 0;
  39         }
  40
  41         /*
  42          * Before trying to mount and use "rootfs_data" let's check if there is
  43          * extroot configured. Following call will handle reading config from
  44          * the "rootfs_data" on its own.
  45          */
  46         extroot_prefix = "";
  47         if (!mount_extroot()) {
  48                 fprintf(stderr, "fs-state: switched to extroot\n");
  49                 return 0;
  50         }
  51
  52         /* There isn't extroot, so just try to mount "rootfs_data" */
  53         switch (volume_identify(v)) {
  54         case FS_NONE:
  55         case FS_DEADCODE:
  56                 /*
  57                  * Filesystem isn't ready yet and we are in the preinit, so we
  58                  * can't afford waiting for it. Use tmpfs for now and handle it
  59                  * properly in the "done" call.
  60                  */
  61                 return ramoverlay();
  62
  63         case FS_JFFS2:
  64         case FS_UBIFS:
  65                 mount_overlay(v);
  66                 break;
  67
  68         case FS_SNAPSHOT:
  69                 mount_snapshot(v);
  70                 break;
  71         }
  72
  73         return 0;
  74 }
  75
  76 static int
  77 stop(int argc, char *argv[1])
  78 {
  79         if (!getenv("SHUTDOWN"))
  80                 return -1;
  81
  82         return 0;
  83 }
  84
  85 /*
  86  * Called at the end of init, it can wait for filesystem if needed.
  87  */
  88 static int
  89 done(int argc, char *argv[1])
  90 {
  91         struct volume *v = volume_find("rootfs_data");
  92
  93         if (!v)
  94                 return -1;
  95
  96         switch (volume_identify(v)) {
  97         case FS_NONE:
  98         case FS_DEADCODE:
  99                 return jffs2_switch(v);
 100         }
 101
 102         return 0;
 103 }
 104
 105 int main(int argc, char **argv)
 106 {
 107         if (argc < 2)
 108                 return start(argc, argv);
 109         if (!strcmp(argv[1], "stop"))
 110                 return stop(argc, argv);
 111         if (!strcmp(argv[1], "done"))
 112                 return done(argc, argv);
 113         return -1;
 114 }