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 <sys/types.h>
  16 #include <sys/stat.h>
  17 #include <unistd.h>
  18 #include <stdio.h>
  19 #include <stdlib.h>
  20
  21 #include <libubox/ulog.h>
  22
  23 #include "libfstools/libfstools.h"
  24 #include "libfstools/volume.h"
  25
  26 /*
  27  * Called in the early (PREINIT) stage, when we immediately need some writable
  28  * filesystem.
  29  */
  30 static int
  31 start(int argc, char *argv[1])
  32 {
  33         struct volume *root;
  34         struct volume *data = volume_find("rootfs_data");
  35         struct stat s;
  36
  37         if (!getenv("PREINIT") && stat("/tmp/.preinit", &s))
  38                 return -1;
  39
  40         if (!data) {
  41                 root = volume_find("rootfs");
  42                 volume_init(root);
  43                 ULOG_NOTE("mounting /dev/root\n");
  44                 mount("/dev/root", "/", NULL, MS_NOATIME | MS_REMOUNT, 0);
  45         }
  46
  47         /*
  48          * Before trying to mount and use "rootfs_data" let's check if there is
  49          * extroot configured. Following call will handle reading config from
  50          * the "rootfs_data" on its own.
  51          */
  52         extroot_prefix = "";
  53         if (!mount_extroot()) {
  54                 ULOG_NOTE("switched to extroot\n");
  55                 return 0;
  56         }
  57
  58         /* There isn't extroot, so just try to mount "rootfs_data" */
  59         switch (volume_identify(data)) {
  60         case FS_NONE:
  61                 ULOG_WARN("no usable overlay filesystem found, using tmpfs overlay\n");
  62                 return ramoverlay();
  63
  64         case FS_DEADCODE:
  65                 /*
  66                  * Filesystem isn't ready yet and we are in the preinit, so we
  67                  * can't afford waiting for it. Use tmpfs for now and handle it
  68                  * properly in the "done" call.
  69                  */
  70                 ULOG_NOTE("jffs2 not ready yet, using temporary tmpfs overlay\n");
  71                 return ramoverlay();
  72
  73         case FS_JFFS2:
  74         case FS_UBIFS:
  75                 mount_overlay(data);
  76                 break;
  77
  78         case FS_SNAPSHOT:
  79                 mount_snapshot(data);
  80                 break;
  81         }
  82
  83         return 0;
  84 }
  85
  86 static int
  87 stop(int argc, char *argv[1])
  88 {
  89         if (!getenv("SHUTDOWN"))
  90                 return -1;
  91
  92         return 0;
  93 }
  94
  95 /*
  96  * Called at the end of init, it can wait for filesystem if needed.
  97  */
  98 static int
  99 done(int argc, char *argv[1])
 100 {
 101         struct volume *v = volume_find("rootfs_data");
 102
 103         if (!v)
 104                 return -1;
 105
 106         switch (volume_identify(v)) {
 107         case FS_NONE:
 108         case FS_DEADCODE:
 109                 return jffs2_switch(v);
 110
 111         case FS_JFFS2:
 112         case FS_UBIFS:
 113                 fs_state_set("/overlay", FS_STATE_READY);
 114                 break;
 115         }
 116
 117         return 0;
 118 }
 119
 120 int main(int argc, char **argv)
 121 {
 122         if (argc < 2)
 123                 return start(argc, argv);
 124         if (!strcmp(argv[1], "ram"))
 125                 return ramoverlay();
 126         if (!strcmp(argv[1], "stop"))
 127                 return stop(argc, argv);
 128         if (!strcmp(argv[1], "done"))
 129                 return done(argc, argv);
 130         return -1;
 131 }