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Commit e3aeeb4d authored by Ken Sumrall's avatar Ken Sumrall
Browse files

Try to unmount writable filesystems when rebooting 

Ext4 filesystems like to be unmounted before rebooting.  The Android system
doesn't have a traditional Linux init setup, and shutting down the system
was not much more than calling sync(2) and reboot(2).  This adds a new
function to libcutils called android_reboot().  By default, it calls sync()
and then remounts all writable filesystems as read-only and marks them clean.
There is a flag parameter in which the caller can ask for sync() not to be
called, or to not remount the filesystems as read-only.  Then it will call
reboot(2) as directed by the other parameters.  This change also updates
adb, init and toolbox to call the new android_reboot() function.
Fixes bugs 3350709 and 3495575.

Change-Id: I16d71ffce3134310d7a260f61ec6f4dd204124a7
parent cf015971

adb/services.c

+2 −3
Original line number Diff line number Diff line
@@ -32,7 +32,7 @@ 
#    include <netdb.h>

#  endif

#else

#  include <sys/reboot.h>

#  include <cutils/android_reboot.h>

#endif



typedef struct stinfo stinfo;
@@ -193,8 +193,7 @@ void reboot_service(int fd, void *arg) 
        waitpid(pid, &ret, 0);

    }



    ret = __reboot(LINUX_REBOOT_MAGIC1, LINUX_REBOOT_MAGIC2,

                    LINUX_REBOOT_CMD_RESTART2, (char *)arg);

    ret = android_reboot(ANDROID_RB_RESTART2, 0, (char *) arg);

    if (ret < 0) {

        snprintf(buf, sizeof(buf), "reboot failed: %s\n", strerror(errno));

        writex(fd, buf, strlen(buf));

include/cutils/android_reboot.h

0 → 100644
+35 −0
Original line number Diff line number Diff line 
/*

 * Copyright 2011, The Android Open Source Project

 *

 * Licensed under the Apache License, Version 2.0 (the "License");

 * you may not use this file except in compliance with the License.

 * You may obtain a copy of the License at

 *

 *     http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */



#ifndef __CUTILS_ANDROID_REBOOT_H__

#define __CUTILS_ANDROID_REBOOT_H__



__BEGIN_DECLS



/* Commands */

#define ANDROID_RB_RESTART  0xDEAD0001

#define ANDROID_RB_POWEROFF 0xDEAD0002

#define ANDROID_RB_RESTART2 0xDEAD0003



/* Flags */

#define ANDROID_RB_FLAG_NO_SYNC       0x1

#define ANDROID_RB_FLAG_NO_REMOUNT_RO 0x2



int android_reboot(int cmd, int flags, char *arg);



__END_DECLS



#endif /* __CUTILS_ANDROID_REBOOT_H__ */

init/signal_handler.c

+2 −4
Original line number Diff line number Diff line
@@ -23,7 +23,7 @@ 
#include <sys/socket.h>

#include <sys/wait.h>

#include <cutils/sockets.h>

#include <sys/reboot.h>

#include <cutils/android_reboot.h>



#include "init.h"

#include "list.h"
@@ -96,9 +96,7 @@ static int wait_for_one_process(int block) 
                ERROR("critical process '%s' exited %d times in %d minutes; "

                      "rebooting into recovery mode\n", svc->name,

                      CRITICAL_CRASH_THRESHOLD, CRITICAL_CRASH_WINDOW / 60);

                sync();

                __reboot(LINUX_REBOOT_MAGIC1, LINUX_REBOOT_MAGIC2,

                         LINUX_REBOOT_CMD_RESTART2, "recovery");

                android_reboot(ANDROID_RB_RESTART2, 0, "recovery");

                return 0;

            }

        } else {

libcutils/Android.mk

+1 −1
Original line number Diff line number Diff line
@@ -109,7 +109,7 @@ else #!sim 
# ========================================================

include $(CLEAR_VARS)

LOCAL_MODULE := libcutils

LOCAL_SRC_FILES := $(commonSources) ashmem-dev.c mq.c

LOCAL_SRC_FILES := $(commonSources) ashmem-dev.c mq.c android_reboot.c



ifeq ($(TARGET_ARCH),arm)

LOCAL_SRC_FILES += arch-arm/memset32.S

libcutils/android_reboot.c

0 → 100644
+134 −0
Original line number Diff line number Diff line 
/*

 * Copyright 2011, The Android Open Source Project

 *

 * Licensed under the Apache License, Version 2.0 (the "License");

 * you may not use this file except in compliance with the License.

 * You may obtain a copy of the License at

 *

 *     http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */



#include <unistd.h>

#include <sys/reboot.h>

#include <sys/types.h>

#include <sys/stat.h>

#include <fcntl.h>

#include <stdio.h>

#include <string.h>



#include <cutils/android_reboot.h>



/* Check to see if /proc/mounts contains any writeable filesystems

 * backed by a block device.

 * Return true if none found, else return false.

 */

static int remount_ro_done(void)

{

    FILE *f;

    char mount_dev[256];

    char mount_dir[256];

    char mount_type[256];

    char mount_opts[256];

    int mount_freq;

    int mount_passno;

    int match;

    int found_rw_fs = 0;



    f = fopen("/proc/mounts", "r");

    if (! f) {

        /* If we can't read /proc/mounts, just give up */

        return 1;

    }



    do {

        match = fscanf(f, "%255s %255s %255s %255s %d %d\n",

                       mount_dev, mount_dir, mount_type,

                       mount_opts, &mount_freq, &mount_passno);

        mount_dev[255] = 0;

        mount_dir[255] = 0;

        mount_type[255] = 0;

        mount_opts[255] = 0;

        if ((match == 6) && !strncmp(mount_dev, "/dev/block", 10) && strstr(mount_opts, "rw")) {

            found_rw_fs = 1;

            break;

        }

    } while (match != EOF);



    fclose(f);



    return !found_rw_fs;

}



/* Remounting filesystems read-only is difficult when there are files

 * opened for writing or pending deletes on the filesystem.  There is

 * no way to force the remount with the mount(2) syscall.  The magic sysrq

 * 'u' command does an emergency remount read-only on all writable filesystems

 * that have a block device (i.e. not tmpfs filesystems) by calling

 * emergency_remount(), which knows how to force the remount to read-only.

 * Unfortunately, that is asynchronous, and just schedules the work and

 * returns.  The best way to determine if it is done is to read /proc/mounts

 * repeatedly until there are no more writable filesystems mounted on

 * block devices.

 */

static void remount_ro(void)

{

    int fd, cnt = 0;



    /* Trigger the remount of the filesystems as read-only,

     * which also marks them clean.

     */

    fd = open("/proc/sysrq-trigger", O_WRONLY);

    if (fd < 0) {

        return;

    }

    write(fd, "u", 1);

    close(fd);





    /* Now poll /proc/mounts till it's done */

    while (!remount_ro_done() && (cnt < 50)) {

        usleep(100000);

        cnt++;

    }



    return;

}





int android_reboot(int cmd, int flags, char *arg)

{

    int ret;



    if (!(flags & ANDROID_RB_FLAG_NO_SYNC))

        sync();



    if (!(flags & ANDROID_RB_FLAG_NO_REMOUNT_RO))

        remount_ro();



    switch (cmd) {

        case ANDROID_RB_RESTART:

            ret = reboot(RB_AUTOBOOT);

            break;



        case ANDROID_RB_POWEROFF:

            ret = reboot(RB_POWER_OFF);

            break;



        case ANDROID_RB_RESTART2:

            ret = __reboot(LINUX_REBOOT_MAGIC1, LINUX_REBOOT_MAGIC2,

                           LINUX_REBOOT_CMD_RESTART2, arg);

            break;



        default:

            ret = -1;

    }



    return ret;

}