Enable system partition compression

* Prerequisites: external/f2fs-tools: sload compression support
* Must work with corresponding changes in system/extras repository
* If Board config does not change, it falls back to old behavior,
  i.e. no compression for the system partition
* Kernel f2fs compression support is a prerequisite if the Board config
  enables the compression (see below)
* Necessary board config change
 (e.g. device/<vendor>/<product>/BoardConfig-common.mk)

BOARD_SYSTEMIMAGE_FILE_SYSTEM_TYPE := f2fs
BOARD_SYSTEMIMAGE_PARTITION_RESERVED_SIZE := 200000000
BOARD_SYSTEMIMAGE_FILE_SYSTEM_COMPRESS := true
BOARD_SYSTEMIMAGE_F2FS_SLOAD_COMPRESS_FLAGS := <sload compress sub-options>

Setting BOARD_SYSTEMIMAGE_FILE_SYSTEM_COMPRESS to true enables both the
compression support when the initial empty file system be made (mkfs.f2fs)
and the compression flag (-c) when the system image files be side-loaded
by sload.

Sload compress sub-options (i.e. options other than -c) will be provided
by BOARD_SYSTEMIMAGE_F2FS_SLOAD_COMPRESS_FLAGS.   If it is not given, or
is empty, the default sub-options will be used

Please refer to the sload.f2fs manual page.

Setting BOARD_SYSTEMIMAGE_FILE_SYSTEM_TYPE to f2fs is trivially necessary.

* File system table (fstab), notably the file 'fstab.hardware', should
  also changed:
  - The file type must be changed to f2fs
  - Perhaps also other f2fs-specific options

Bug: 170918499
Test: Pixel4a userdebug build (from build id 6918751)
Signed-off-by: Robin Hsu <robinhsu@google.com>
Change-Id: Id9d67b5cb35dc806e06ff1320e89114abc996a28

2 files changed, 14 insertions, 1 deletions

diff --git a/core/Makefile b/core/Makefile
index 6656a1999b..6dfb4621bf 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -1394,6 +1394,8 @@ $(if $(filter $(2),system),\
     $(if $(BOARD_SYSTEMIMAGE_PARTITION_SIZE),$(hide) echo "system_size=$(BOARD_SYSTEMIMAGE_PARTITION_SIZE)" >> $(1))
     $(if $(INTERNAL_SYSTEM_OTHER_PARTITION_SIZE),$(hide) echo "system_other_size=$(INTERNAL_SYSTEM_OTHER_PARTITION_SIZE)" >> $(1))
     $(if $(BOARD_SYSTEMIMAGE_FILE_SYSTEM_TYPE),$(hide) echo "system_fs_type=$(BOARD_SYSTEMIMAGE_FILE_SYSTEM_TYPE)" >> $(1))
+    $(if $(BOARD_SYSTEMIMAGE_FILE_SYSTEM_COMPRESS),$(hide) echo "system_fs_compress=$(BOARD_SYSTEMIMAGE_FILE_SYSTEM_COMPRESS)" >> $(1))
+    $(if $(BOARD_SYSTEMIMAGE_F2FS_SLOAD_COMPRESS_FLAGS),$(hide) echo "system_f2fs_sldc_flags=$(BOARD_SYSTEMIMAGE_F2FS_SLOAD_COMPRESS_FLAGS)" >> $(1))
     $(if $(BOARD_SYSTEMIMAGE_EXTFS_INODE_COUNT),$(hide) echo "system_extfs_inode_count=$(BOARD_SYSTEMIMAGE_EXTFS_INODE_COUNT)" >> $(1))
     $(if $(BOARD_SYSTEMIMAGE_EXTFS_RSV_PCT),$(hide) echo "system_extfs_rsv_pct=$(BOARD_SYSTEMIMAGE_EXTFS_RSV_PCT)" >> $(1))
     $(if $(BOARD_SYSTEMIMAGE_JOURNAL_SIZE),$(hide) echo "system_journal_size=$(BOARD_SYSTEMIMAGE_JOURNAL_SIZE)" >> $(1))
diff --git a/tools/releasetools/build_image.py b/tools/releasetools/build_image.py
index 6487b9b8e2..c03fac104d 100755
--- a/tools/releasetools/build_image.py
+++ b/tools/releasetools/build_image.py
@@ -350,8 +350,17 @@ def BuildImageMkfs(in_dir, prop_dict, out_file, target_out, fs_config):
       build_command.append("--prjquota")
     if (needs_casefold):
       build_command.append("--casefold")
-    if (needs_compress):
+    if (needs_compress or prop_dict.get("system_fs_compress") == "true"):
       build_command.append("--compression")
+    if (prop_dict.get("system_fs_compress") == "true"):
+      build_command.append("--sldc")
+      if (prop_dict.get("system_f2fs_sldc_flags") == None):
+        build_command.append(str(0))
+      else:
+        sldc_flags_str = prop_dict.get("system_f2fs_sldc_flags")
+        sldc_flags = sldc_flags_str.split()
+        build_command.append(str(len(sldc_flags)))
+        build_command.extend(sldc_flags)
   else:
     raise BuildImageError(
         "Error: unknown filesystem type: {}".format(fs_type))
@@ -546,6 +555,8 @@ def ImagePropFromGlobalDict(glob_dict, mount_point):
       "extfs_sparse_flag",
       "erofs_sparse_flag",
       "squashfs_sparse_flag",
+      "system_fs_compress",
+      "system_f2fs_sldc_flags",
       "f2fs_sparse_flag",
       "skip_fsck",
       "ext_mkuserimg",