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 = volume_find("rootfs");
  31         struct volume *data = volume_find("rootfs_data");
  32
  33         if (data && find_mount_point(data->blk, 0))
  34                 return -1;
  35
  36         if (root && find_mount_point(root->blk, 0))
  37                 return -1;
  38
  39         if (!data) {
  40                 volume_init(root);
  41                 ULOG_NOTE("mounting /dev/root\n");
  42                 mount("/dev/root", "/", NULL, MS_NOATIME | MS_REMOUNT, 0);
  43         }
  44
  45         /*
  46          * Before trying to mount and use "rootfs_data" let's check if there is
  47          * extroot configured. Following call will handle reading config from
  48          * the "rootfs_data" on its own.
  49          */
  50         extroot_prefix = "";
  51         if (!mount_extroot()) {
  52                 ULOG_NOTE("switched to extroot\n");
  53                 return 0;
  54         }
  55
  56         /* There isn't extroot, so just try to mount "rootfs_data" */
  57         switch (volume_identify(data)) {
  58         case FS_NONE:
  59                 ULOG_WARN("no usable overlay filesystem found, using tmpfs overlay\n");
  60                 return ramoverlay();
  61
  62         case FS_DEADCODE:
  63                 /*
  64                  * Filesystem isn't ready yet and we are in the preinit, so we
  65                  * can't afford waiting for it. Use tmpfs for now and handle it
  66                  * properly in the "done" call.
  67                  */
  68                 ULOG_NOTE("jffs2 not ready yet, using temporary tmpfs overlay\n");
  69                 return ramoverlay();
  70
  71         case FS_JFFS2:
  72         case FS_UBIFS:
  73                 mount_overlay(data);
  74                 break;
  75
  76         case FS_SNAPSHOT:
  77                 mount_snapshot(data);
  78                 break;
  79         }
  80
  81         return 0;
  82 }
  83
  84 static int
  85 stop(int argc, char *argv[1])
  86 {
  87         if (!getenv("SHUTDOWN"))
  88                 return -1;
  89
  90         return 0;
  91 }
  92
  93 /*
  94  * Called at the end of init, it can wait for filesystem if needed.
  95  */
  96 static int
  97 done(int argc, char *argv[1])
  98 {
  99         struct volume *v = volume_find("rootfs_data");
 100
 101         if (!v)
 102                 return -1;
 103
 104         switch (volume_identify(v)) {
 105         case FS_NONE:
 106         case FS_DEADCODE:
 107                 return jffs2_switch(v);
 108
 109         case FS_JFFS2:
 110         case FS_UBIFS:
 111                 fs_state_set("/overlay", FS_STATE_READY);
 112                 break;
 113         }
 114
 115         return 0;
 116 }
 117
 118 int main(int argc, char **argv)
 119 {
 120         if (argc < 2)
 121                 return start(argc, argv);
 122         if (!strcmp(argv[1], "ram"))
 123                 return ramoverlay();
 124         if (!strcmp(argv[1], "stop"))
 125                 return stop(argc, argv);
 126         if (!strcmp(argv[1], "done"))
 127                 return done(argc, argv);
 128         return -1;
 129 }