Merge changes from topic "resgidz"

* changes:
  Add reserved disk GID to critical component.
  Set reserved GID when setting reserved blocks.
  Allocate GID to use reserved disk space.

fs_mgr/fs_mgr.cpp

@@ -38,6 +38,7 @@
 #include <android-base/properties.h>
 #include <android-base/stringprintf.h>
 #include <android-base/unique_fd.h>
+#include <cutils/android_filesystem_config.h>
 #include <cutils/android_reboot.h>
 #include <cutils/partition_utils.h>
 #include <cutils/properties.h>
@@ -353,7 +354,7 @@ static void tune_reserved_size(const char* blk_device, const struct fstab_rec* r
         reserved_blocks = max_reserved_blocks;
     }
 
-    if (ext4_r_blocks_count(sb) == reserved_blocks) {
+    if ((ext4_r_blocks_count(sb) == reserved_blocks) && (sb->s_def_resgid == AID_RESERVED_DISK)) {
         return;
     }
 
@@ -363,11 +364,12 @@ static void tune_reserved_size(const char* blk_device, const struct fstab_rec* r
         return;
     }
 
-    char buf[32];
-    const char* argv[] = {TUNE2FS_BIN, "-r", buf, blk_device};
-
-    snprintf(buf, sizeof(buf), "%" PRIu64, reserved_blocks);
     LINFO << "Setting reserved block count on " << blk_device << " to " << reserved_blocks;
+
+    auto reserved_blocks_str = std::to_string(reserved_blocks);
+    auto reserved_gid_str = std::to_string(AID_RESERVED_DISK);
+    const char* argv[] = {
+        TUNE2FS_BIN, "-r", reserved_blocks_str.c_str(), "-g", reserved_gid_str.c_str(), blk_device};
     if (!run_tune2fs(argv, ARRAY_SIZE(argv))) {
         LERROR << "Failed to run " TUNE2FS_BIN " to set the number of reserved blocks on "
                << blk_device;

libcutils/include/private/android_filesystem_config.h

@@ -122,6 +122,7 @@
 #define AID_AUTOMOTIVE_EVS 1062  /* Automotive rear and surround view system */
 #define AID_LOWPAN 1063          /* LoWPAN subsystem */
 #define AID_HSM 1064             /* hardware security module subsystem */
+#define AID_RESERVED_DISK 1065   /* GID that has access to reserved disk space */
 /* Changes to this file must be made in AOSP, *not* in internal branches. */
 
 #define AID_SHELL 2000 /* adb and debug shell user */

rootdir/init.zygote32.rc

@@ -2,7 +2,7 @@ service zygote /system/bin/app_process -Xzygote /system/bin --zygote --start-sys
     class main
     priority -20
     user root
-    group root readproc
+    group root readproc reserved_disk
     socket zygote stream 660 root system
     onrestart write /sys/android_power/request_state wake
     onrestart write /sys/power/state on

rootdir/init.zygote32_64.rc

@@ -2,7 +2,7 @@ service zygote /system/bin/app_process32 -Xzygote /system/bin --zygote --start-s
     class main
     priority -20
     user root
-    group root readproc
+    group root readproc reserved_disk
     socket zygote stream 660 root system
     onrestart write /sys/android_power/request_state wake
     onrestart write /sys/power/state on
@@ -17,7 +17,7 @@ service zygote_secondary /system/bin/app_process64 -Xzygote /system/bin --zygote
     class main
     priority -20
     user root
-    group root readproc
+    group root readproc reserved_disk
     socket zygote_secondary stream 660 root system
     onrestart restart zygote
     writepid /dev/cpuset/foreground/tasks

rootdir/init.zygote64.rc

@@ -2,7 +2,7 @@ service zygote /system/bin/app_process64 -Xzygote /system/bin --zygote --start-s
     class main
     priority -20
     user root
-    group root readproc
+    group root readproc reserved_disk
     socket zygote stream 660 root system
     onrestart write /sys/android_power/request_state wake
     onrestart write /sys/power/state on

rootdir/init.zygote64_32.rc

@@ -2,7 +2,7 @@ service zygote /system/bin/app_process64 -Xzygote /system/bin --zygote --start-s
     class main
     priority -20
     user root
-    group root readproc
+    group root readproc reserved_disk
     socket zygote stream 660 root system
     onrestart write /sys/android_power/request_state wake
     onrestart write /sys/power/state on
@@ -17,7 +17,7 @@ service zygote_secondary /system/bin/app_process32 -Xzygote /system/bin --zygote
     class main
     priority -20
     user root
-    group root readproc
+    group root readproc reserved_disk
     socket zygote_secondary stream 660 root system
     onrestart restart zygote
     writepid /dev/cpuset/foreground/tasks