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 <libubox/ulog.h>
  19
  20 #include "libfstools/libfstools.h"
  21 #include "libfstools/volume.h"
  22
  23 /*
  24  * Called in the early (PREINIT) stage, when we immediately need some writable
  25  * filesystem.
  26  */
  27 static int
  28 start(int argc, char *argv[1])
  29 {
  30         struct volume *root;
  31         struct volume *data = volume_find("rootfs_data");
  32
  33         if (!getenv("PREINIT"))
  34                 return -1;
  35
  36         if (!data) {
  37                 root = volume_find("rootfs");
  38                 volume_init(root);
  39                 ULOG_NOTE("mounting /dev/root\n");
  40                 mount("/dev/root", "/", NULL, MS_NOATIME | MS_REMOUNT, 0);
  41         }
  42
  43         /*
  44          * Before trying to mount and use "rootfs_data" let's check if there is
  45          * extroot configured. Following call will handle reading config from
  46          * the "rootfs_data" on its own.
  47          */
  48         extroot_prefix = "";
  49         if (!mount_extroot()) {
  50                 ULOG_NOTE("switched to extroot\n");
  51                 return 0;
  52         }
  53
  54         /* There isn't extroot, so just try to mount "rootfs_data" */
  55         switch (volume_identify(data)) {
  56         case FS_NONE:
  57                 ULOG_WARN("no usable overlay filesystem found, using tmpfs overlay\n");
  58                 return ramoverlay();
  59
  60         case FS_DEADCODE:
  61                 /*
  62                  * Filesystem isn't ready yet and we are in the preinit, so we
  63                  * can't afford waiting for it. Use tmpfs for now and handle it
  64                  * properly in the "done" call.
  65                  */
  66                 ULOG_NOTE("jffs2 not ready yet, using temporary tmpfs overlay\n");
  67                 return ramoverlay();
  68
  69         case FS_JFFS2:
  70         case FS_UBIFS:
  71                 mount_overlay(data);
  72                 break;
  73
  74         case FS_SNAPSHOT:
  75                 mount_snapshot(data);
  76                 break;
  77         }
  78
  79         return 0;
  80 }
  81
  82 static int
  83 stop(int argc, char *argv[1])
  84 {
  85         if (!getenv("SHUTDOWN"))
  86                 return -1;
  87
  88         return 0;
  89 }
  90
  91 /*
  92  * Called at the end of init, it can wait for filesystem if needed.
  93  */
  94 static int
  95 done(int argc, char *argv[1])
  96 {
  97         struct volume *v = volume_find("rootfs_data");
  98
  99         if (!v)
 100                 return -1;
 101
 102         switch (volume_identify(v)) {
 103         case FS_NONE:
 104         case FS_DEADCODE:
 105                 return jffs2_switch(v);
 106
 107         case FS_JFFS2:
 108         case FS_UBIFS:
 109                 fs_state_set("/overlay", FS_STATE_READY);
 110                 break;
 111         }
 112
 113         return 0;
 114 }
 115
 116 int main(int argc, char **argv)
 117 {
 118         if (argc < 2)
 119                 return start(argc, argv);
 120         if (!strcmp(argv[1], "ram"))
 121                 return ramoverlay();
 122         if (!strcmp(argv[1], "stop"))
 123                 return stop(argc, argv);
 124         if (!strcmp(argv[1], "done"))
 125                 return done(argc, argv);
 126         return -1;
 127 }