am 70987108: Merge "Try to unmount writable filesystems when rebooting" into honeycomb-mr1

* commit '7098710805bbf771d7b76c798951f4648539dadb':
  Try to unmount writable filesystems when rebooting

adb/services.c

@@ -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,
+    ret = android_reboot(ANDROID_RB_RESTART2, 0, (char *) arg);
-                    LINUX_REBOOT_CMD_RESTART2, (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

@@ -0,0 +1,35 @@
+/*
+ * 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

@@ -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();
+                android_reboot(ANDROID_RB_RESTART2, 0, "recovery");
-                __reboot(LINUX_REBOOT_MAGIC1, LINUX_REBOOT_MAGIC2,
-                         LINUX_REBOOT_CMD_RESTART2, "recovery");
                 return 0;
             }
         } else {

libcutils/Android.mk

@@ -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

@@ -0,0 +1,134 @@
+/*
+ * 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;
+}
+

toolbox/reboot.c

@@ -1,7 +1,7 @@
 #include <errno.h>
 #include <stdio.h>
 #include <stdlib.h>
-#include <sys/reboot.h>
+#include <cutils/android_reboot.h>
 #include <unistd.h>
 
 int reboot_main(int argc, char *argv[])
@@ -9,6 +9,7 @@ int reboot_main(int argc, char *argv[])
     int ret;
     int nosync = 0;
     int poweroff = 0;
+    int flags = 0;
 
     opterr = 0;
     do {
@@ -38,15 +39,16 @@ int reboot_main(int argc, char *argv[])
         exit(EXIT_FAILURE);
     }
 
-    if(!nosync)
+    if(nosync)
-        sync();
+        /* also set NO_REMOUNT_RO as remount ro includes an implicit sync */
+        flags = ANDROID_RB_FLAG_NO_SYNC | ANDROID_RB_FLAG_NO_REMOUNT_RO;
 
     if(poweroff)
-        ret = __reboot(LINUX_REBOOT_MAGIC1, LINUX_REBOOT_MAGIC2, LINUX_REBOOT_CMD_POWER_OFF, NULL);
+        ret = android_reboot(ANDROID_RB_POWEROFF, flags, 0);
     else if(argc > optind)
-        ret = __reboot(LINUX_REBOOT_MAGIC1, LINUX_REBOOT_MAGIC2, LINUX_REBOOT_CMD_RESTART2, argv[optind]);
+        ret = android_reboot(ANDROID_RB_RESTART2, flags, argv[optind]);
     else
-        ret = reboot(RB_AUTOBOOT);
+        ret = android_reboot(ANDROID_RB_RESTART, flags, 0);
     if(ret < 0) {
         perror("reboot");
         exit(EXIT_FAILURE);

toolbox/wipe.c

@@ -5,7 +5,7 @@
 #include <string.h>
 #include <errno.h>
 #include <sys/types.h>
-#include <sys/reboot.h>
+#include <cutils/android_reboot.h>
 #include <sys/stat.h>
 
 #ifndef PATH_MAX
@@ -63,7 +63,7 @@ int wipe_main (int argc, char *argv[])
 		wipe ("/system");
         wipe ("/data");
 		fprintf(stdout, "Device nuked! Rebooting...\n");
-		ret = reboot(RB_AUTOBOOT);
+		ret = android_reboot(ANDROID_RB_RESTART, 0, 0);
 	    if (ret < 0) {
 	        fprintf(stderr, "Reboot failed, %s\n", strerror(errno));
 	        return 1;