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Commit 885b742b authored by doheon1.lee's avatar doheon1.lee Committed by Jeff Sharkey
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Changes of root storage space unmounting time on Zygote Process 

Zygote process forks every child process for launch the SystemServer and other
applications. When child process is forked, unmount storage inherited
from Zygote process is executed before it gains its own root storage
space.
If Zygote have no storage spaces, unmount operations not needed to
get relevant permission storage space.
Thus unmount is executed only once shortly before the SystemServer is forked.
And the child processes do not unmount its inherited root storage space.

Change-Id: I311ca7ea2c93085f42579f8cf8bdc7ef1d570a04
parent cf3f0a11

core/java/com/android/internal/os/Zygote.java

+6 −0
Original line number Diff line number Diff line
@@ -149,6 +149,12 @@ public final class Zygote { 
    native private static int nativeForkSystemServer(int uid, int gid, int[] gids, int debugFlags,

            int[][] rlimits, long permittedCapabilities, long effectiveCapabilities);



    /**

     * Zygote unmount storage space on initializing.

     * This method is called once.

     */

    native protected static void nativeUnmountStorageOnInit();



    private static void callPostForkChildHooks(int debugFlags, boolean isSystemServer,

            String instructionSet) {

        VM_HOOKS.postForkChild(debugFlags, isSystemServer, instructionSet);

core/java/com/android/internal/os/ZygoteInit.java

+3 −0
Original line number Diff line number Diff line
@@ -643,6 +643,9 @@ public class ZygoteInit { 
            // Zygote.

            Trace.setTracingEnabled(false);



            // Zygote process unmounts root storage spaces.

            Zygote.nativeUnmountStorageOnInit();



            if (startSystemServer) {

                startSystemServer(abiList, socketName);

            }

core/jni/com_android_internal_os_Zygote.cpp

+13 −4
Original line number Diff line number Diff line
@@ -302,9 +302,6 @@ static bool MountEmulatedStorage(uid_t uid, jint mount_mode, 
        return false;

    }



    // Unmount storage provided by root namespace and mount requested view

    UnmountTree("/storage");



    String8 storageSource;

    if (mount_mode == MOUNT_EXTERNAL_DEFAULT) {

        storageSource = "/mnt/runtime/default";
@@ -667,12 +664,24 @@ static jint com_android_internal_os_Zygote_nativeForkSystemServer( 
  return pid;

}



static void com_android_internal_os_Zygote_nativeUnmountStorageOnInit(JNIEnv* env, jclass) {

    // Zygote process unmount root storage space initially before every child processes are forked.

    // Every forked child processes (include SystemServer) only mount their own root storage space

    // And no need unmount storage operation in MountEmulatedStorage method.

    // Zygote process does not utilize root storage spaces and unshared its mount namespace from the ART.



    UnmountTree("/storage");

    return;

}



static const JNINativeMethod gMethods[] = {

    { "nativeForkAndSpecialize",

      "(II[II[[IILjava/lang/String;Ljava/lang/String;[ILjava/lang/String;Ljava/lang/String;)I",

      (void *) com_android_internal_os_Zygote_nativeForkAndSpecialize },

    { "nativeForkSystemServer", "(II[II[[IJJ)I",

      (void *) com_android_internal_os_Zygote_nativeForkSystemServer }

      (void *) com_android_internal_os_Zygote_nativeForkSystemServer },

    { "nativeUnmountStorageOnInit", "()V",

      (void *) com_android_internal_os_Zygote_nativeUnmountStorageOnInit }

};



int register_com_android_internal_os_Zygote(JNIEnv* env) {