adb remount之后，OTA 升级失败的问题

MTK平台,remount后ota升级失败

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userdebug版本，remount升级失败

adb root
adb remount
然后push了一堆东西进去，ota升级的时候会报空间不够，我们先看mtk的debug log

 473   473 I update_engine: [1101/114216.247577:INFO:dynamic_partition_control_android.cc(197)] Loaded metadata from slot A in /dev/block/platform/bootdevice/by-name/super
 473   473 I update_engine: [1101/114216.247946:INFO:boot_control_android.cc(312)] Removing group main_b
 473   473 I update_engine: [1101/114216.248105:INFO:boot_control_android.cc(343)] Added group main_b with size 1844969472
 473   473 I /system/bin/update_engine: [liblp]Partition vendor_b will resize from 0 bytes to 327540736 bytes
 473   473 I update_engine: [1101/114216.248254:INFO:boot_control_android.cc(360)] Added partition vendor_b to group main_b with size 327540736
 473   473 I /system/bin/update_engine: [liblp]Partition product_b will resize from 0 bytes to 252170240 bytes
 473   473 I update_engine: [1101/114216.248382:INFO:boot_control_android.cc(360)] Added partition product_b to group main_b with size 252170240
 473   473 E /system/bin/update_engine: [liblp]Not enough free space to expand partition: system_b
 473   473 E update_engine: [1101/114216.248480:ERROR:boot_control_android.cc(356)] Cannot resize partition system_b to size 1154273280. Not enough space?
 473   473 E update_engine: [1101/114216.248544:ERROR:delta_performer.cc(998)] Unable to initialize partition metadata for slot B
 473   473 E update_engine: [1101/114216.248630:ERROR:download_action.cc(336)] Error ErrorCode::kInstallDeviceOpenError (7) in DeltaPerformer's Write method when processing the received payload -- Terminating processing
 473   473 I update_engine: [1101/114216.249175:INFO:multi_range_http_fetcher.cc(177)] Received transfer terminated.
 473   473 I update_engine: [1101/114216.249358:INFO:multi_range_http_fetcher.cc(129)] TransferEnded w/ code 200
 473   473 I update_engine: [1101/114216.249451:INFO:multi_range_http_fetcher.cc(131)] Terminating.
1236  1524 V FespxProcessor: onMultibfDataReceived: 8 index 0 size 4096 mPreUploadRollbackDataSize 131072
 473   473 I update_engine: [1101/114216.253259:INFO:action_processor.cc(116)] ActionProcessor: finished DownloadAction with code ErrorCode::kInstallDeviceOpenError
 473   473 I update_engine: [1101/114216.253452:INFO:action_processor.cc(121)] ActionProcessor: Aborting processing due to failure.
 473   473 I update_engine: [1101/114216.253521:INFO:update_attempter_android.cc(454)] Processing Done.
 473   473 I update_engine: [1101/114216.253568:INFO:dynamic_partition_control_android.cc(151)] Destroying [] from device mapper
3254  3272 D clifeOTA: onStatusUpdate  status: 0
 473   473 I update_engine: [1101/114216.254265:INFO:metrics_repo

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原因分析：

看这句
ERROR:boot_control_android.cc(356)] Cannot resize partition system_b to size 1154273280. Not enough space?
意思是空间不够，查看储存，16G内存只占用了5G多，实际内存多，为什么内存不够， 主要是看对分区的内存，结合MTKAB分区这个链接里面的分区，partition_ab_dynamic.xml，或者partition_dynamic.xml 这两个文件可以看到对super分区和userdata分区的大小，如userdata分区6291456* 512 / 1024 /1024 /1024 =3 G，表示用户空间占3G，出错原因主要是super分区的大小导致的，一般情况下是16G以上的内存的话， AB分区各占1.5G左右，然后adb remount之后会产生一个overlay的scratch分区，这个分区实际上占用在super分区上的，具体占用多少内存还是看 product，vendor，system三个目录的大小，这样，如果super分区太小的话，在AB OTA升级的时候，就是导致动态分区不够，导致升级失败，因OTA升级时不会清除scratch分区的，我这里为什么会报错，是因为改了内存，从16G降到了8G，然后其他同事改分区的时候只减小修改了super分区大小为3G多，所以userdebug版本，remount之后，overlay占用了super分区，导致升级slot b分区的时候，动态分配分区内存就不够，所以升级失败。

<?xml version="1.0" encoding="utf-8"?>
<partition lba="31457280">

<entry type="{0FC63DAF-8483-4772-8E79-3D69D8477DE4}" size="6144" name="proinfo"/>
	<entry type="{0FC63DAF-8483-4772-8E79-3D69D8477DE4}" size="30720" name="cam_vpu1_a"/>
	<entry type="{0FC63DAF-8483-4772-8E79-3D69D8477DE4}" size="30720" name="cam_vpu2_a"/>
	<entry type="{0FC63DAF-8483-4772-8E79-3D69D8477DE4}" size="30720" name="cam_vpu3_a"/>
	<entry type="{0FC63DAF-8483-4772-8E79-3D69D8477DE4}" size="30720" name="cam_vpu1_b"/>
	<entry type="{0FC63DAF-8483-4772-8E79-3D69D8477DE4}" size="30720" name="cam_vpu2_b"/>
	<entry type="{0FC63DAF-8483-4772-8E79-3D69D8477DE4}" size="30720" name="cam_vpu3_b"/>
	
	<entry type="{0FC63DAF-8483-4772-8E79-3D69D8477DE4}" size="10240" name="nvram"/>
	<entry type="{0FC63DAF-8483-4772-8E79-3D69D8477DE4}" size="20480" name="protect1"/>
	<entry type="{0FC63DAF-8483-4772-8E79-3D69D8477DE4}" size="20480" name="protect2"/>
	<entry type="{0FC63DAF-8483-4772-8E79-3D69D8477DE4}" size="98304" name="persist"/>
	<entry type="{0FC63DAF-8483-4772-8E79-3D69D8477DE4}" size="16384" name="nvcfg"/>
	<entry type="{0FC63DAF-8483-4772-8E79-3D69D8477DE4}" size="512" name="seccfg"/>
	
	<entry type="{0FC63DAF-8483-4772-8E79-3D69D8477DE4}" size="2048" name="lk_a"/>
	<entry type="{0FC63DAF-8483-4772-8E79-3D69D8477DE4}" size="2048" name="lk_b"/>
	
	<entry type="{0FC63DAF-8483-4772-8E79-3D69D8477DE4}" size="65536" name="boot_a"/>
	<entry type="{0FC63DAF-8483-4772-8E79-3D69D8477DE4}" size="65536" name="boot_b"/>
	
	<!-- <entry type="{0FC63DAF-8483-4772-8E79-3D69D8477DE4}" size="65536" name="recovery"/> -->
	<entry type="{0FC63DAF-8483-4772-8E79-3D69D8477DE4}" size="1024" name="para"/>
	<entry type="{0FC63DAF-8483-4772-8E79-3D69D8477DE4}" size="16384" name="logo"/>
	
	<entry type="{0FC63DAF-8483-4772-8E79-3D69D8477DE4}" size="16384" name="dtbo_a"/>
	<entry type="{0FC63DAF-8483-4772-8E79-3D69D8477DE4}" size="16384" name="dtbo_b"/>
	
	<entry type="{0FC63DAF-8483-4772-8E79-3D69D8477DE4}" size="20480" name="expdb"/>
	<entry type="{0FC63DAF-8483-4772-8E79-3D69D8477DE4}" size="2048" name="frp"/>
	<entry type="{0FC63DAF-8483-4772-8E79-3D69D8477DE4}" size="10240" name="tee_a"/>
	<entry type="{0FC63DAF-8483-4772-8E79-3D69D8477DE4}" size="10240" name="tee_b"/>
	
	<entry type="{0FC63DAF-8483-4772-8E79-3D69D8477DE4}" size="4096" name="kb"/>
	<entry type="{0FC63DAF-8483-4772-8E79-3D69D8477DE4}" size="4096" name="dkb"/>
	<entry type="{0FC63DAF-8483-4772-8E79-3D69D8477DE4}" size="65536" name="metadata"/>
	
	<entry type="{0FC63DAF-8483-4772-8E79-3D69D8477DE4}" size="11520" name="vbmeta_a"/>
	<entry type="{0FC63DAF-8483-4772-8E79-3D69D8477DE4}" size="11520" name="vbmeta_b"/>
	<entry type="{0FC63DAF-8483-4772-8E79-3D69D8477DE4}" size="8192" name="nvdata" />
	<entry type="{0FC63DAF-8483-4772-8E79-3D69D8477DE4}" size="4096" name="vbmeta_system_a" />
	<entry type="{0FC63DAF-8483-4772-8E79-3D69D8477DE4}" size="4096" name="vbmeta_system_b" />
	<entry type="{0FC63DAF-8483-4772-8E79-3D69D8477DE4}" size="4096" name="vbmeta_vendor_a" />
	<entry type="{0FC63DAF-8483-4772-8E79-3D69D8477DE4}" size="4096" name="vbmeta_vendor_b" />
	<entry type="{0FC63DAF-8483-4772-8E79-3D69D8477DE4}" size="16769024" name="super"/>
	<!-- <entry type="{0FC63DAF-8483-4772-8E79-3D69D8477DE4}" size="229376" name="cache"/>  -->
	<entry type="{0FC63DAF-8483-4772-8E79-3D69D8477DE4}" size="6291456" name="userdata"/>
</partition>

我们对比前后lpdump分区的区别，adb remount之后,
看分区 Name: scratch

C:\Users\aaa>adb shell
xxxx:/ $ lpdump
Metadata version: 10.0
Metadata size: 844 bytes
Metadata max size: 65536 bytes
Metadata slot count: 3
Partition table:
------------------------
  Name: vendor_a
  Group: main_a
  Attributes: readonly
  Extents:
    0 .. 639727 linear super 2048
------------------------
  Name: vendor_b
  Group: main_b
  Attributes: readonly
  Extents:
------------------------
  Name: product_a
  Group: main_a
  Attributes: readonly
  Extents:
    0 .. 492511 linear super 643072
------------------------
  Name: product_b
  Group: main_b
  Attributes: readonly
  Extents:
------------------------
  Name: system_a
  Group: main_a
  Attributes: readonly
  Extents:
    0 .. 2254431 linear super 1136640
------------------------
  Name: system_b
  Group: main_b
  Attributes: readonly
  Extents:
------------------------
  Name: scratch
  Group: default
  Attributes: none
  Extents:
    0 .. 1295 linear super 641776
    1296 .. 2351 linear super 1135584
    2352 .. 1910119 linear super 3391072
------------------------
Block device table:
------------------------
  Partition name: super
  First sector: 2048
  Size: 3690987520 bytes
  Flags: none
------------------------
Group table:
------------------------
  Name: default
  Maximum size: 0 bytes
  Flags: none
------------------------
  Name: main_a
  Maximum size: 1844969472 bytes
  Flags: none
------------------------
  Name: main_b
  Maximum size: 1844969472 bytes
  Flags: none
------------------------

正常设备lpdump

C:\Users\xxxx>adb shell
xxxx:/ $ lpdump
Metadata version: 10.0
Metadata size: 720 bytes
Metadata max size: 65536 bytes
Metadata slot count: 3
Partition table:
------------------------
  Name: vendor_a
  Group: main_a
  Attributes: readonly
  Extents:
    0 .. 639727 linear super 2048
------------------------
  Name: vendor_b
  Group: main_b
  Attributes: readonly
  Extents:
------------------------
  Name: product_a
  Group: main_a
  Attributes: readonly
  Extents:
    0 .. 492511 linear super 643072
------------------------
  Name: product_b
  Group: main_b
  Attributes: readonly
  Extents:
------------------------
  Name: system_a
  Group: main_a
  Attributes: readonly
  Extents:
    0 .. 2254431 linear super 1136640
------------------------
  Name: system_b
  Group: main_b
  Attributes: readonly
  Extents:
------------------------
Block device table:
------------------------
  Partition name: super
  First sector: 2048
  Size: 3690987520 bytes
  Flags: none
------------------------
Group table:
------------------------
  Name: default
  Maximum size: 0 bytes
  Flags: none
------------------------
  Name: main_a
  Maximum size: 1844969472 bytes
  Flags: none
------------------------
  Name: main_b
  Maximum size: 1844969472 bytes
  Flags: none
------------------------

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解决方案：

1.暂时解决方案，清楚了为什么会失败，那么只需要关掉overlay就行
adb root
adb enable-verity
adb reboot
搞定

2.上面只是短暂解决问题，根本上解决，还是要修改super分区大小
怎么算,比如userdata分区6291456* 512 / 1024 /1024 /1024 =3 G
一个8G的话，一般系统占用时1.5G左右，要想remount没有问题的话，至少需要
1.5 * 2 + overlay分区的占用， 这里的话，我写一个4G， 8388608的，在测试，ok，
注意， 所有加起来的大小不能超过 这个，不然编译不过