commit 120f6b260c268c677735fcef434f9480223725ed
author Jaegeuk Kim <jaegeuk@google.com> Fri Mar 04 15:06:02 2022 -0800
committer Jaegeuk Kim <jaegeuk@google.com> Mon Mar 14 16:59:52 2022 -0700
tree 21c4e42e9e03ef180502a15843db1a676adead01
parent 491004bbfb67e58040febda9a396455a9a5c90a4

Init: add dev.mnt.blk.bootdevice to access device sysfs

This patch adds a new property, 'dev.mnt.root.<mount_point>', which provides,
for example of /data,

1. dm-N
  dev.mnt.dev.data = dm-N
  dev.mnt.blk.data = sdaN or mmcblk0pN
  dev.mnt.rootdisk.data = sda or mmcblk0

2. sdaN or mmcblk0pN
  dev.mnt.dev.data = sdaN or mmcblk0pN
  dev.mnt.blk.data = sdaN or mmcblk0pN
  dev.mnt.rootdisk.data = sda or mmcblk0

Signed-off-by: Jaegeuk Kim <jaegeuk@google.com>
Change-Id: I0a58a62d416f966f26b5de04112c2f9a7eceb22c

rootdir/init.rc

diff --git a/rootdir/init.rc b/rootdir/init.rc
index 224f605..404d7ae 100644
--- a/rootdir/init.rc
+++ b/rootdir/init.rc
@@ -1085,9 +1085,11 @@
     mkdir /dev/sys/fs/by-name 0755 system system
     symlink /sys/fs/f2fs/${dev.mnt.dev.data} /dev/sys/fs/by-name/userdata
 
-    # to access dm-<num> sysfs
+    # dev.mnt.dev.data=dm-N, dev.mnt.blk.data=sdaN/mmcblk0pN, dev.mnt.rootdisk.data=sda/mmcblk0, or
+    # dev.mnt.dev.data=sdaN/mmcblk0pN, dev.mnt.blk.data=sdaN/mmcblk0pN, dev.mnt.rootdisk.data=sda/mmcblk0
     mkdir /dev/sys/block/by-name 0755 system system
     symlink /sys/class/block/${dev.mnt.dev.data} /dev/sys/block/by-name/userdata
+    symlink /sys/class/block/${dev.mnt.rootdisk.data} /dev/sys/block/by-name/rootdisk
 
     # F2FS tuning. Set cp_interval larger than dirty_expire_centisecs, 30 secs,
     # to avoid power consumption when system becomes mostly idle. Be careful
@@ -1099,8 +1101,9 @@
 
     # limit discard size to 128MB in order to avoid long IO latency
     # for filesystem tuning first (dm or sda)
-    # Note that, if dm-<num> is used, sda/mmcblk0 should be tuned in vendor/init.rc
+    # this requires enabling selinux entry for sda/mmcblk0 in vendor side
     write /dev/sys/block/by-name/userdata/queue/discard_max_bytes 134217728
+    write /dev/sys/block/by-name/rootdisk/queue/discard_max_bytes 134217728
 
     # Permissions for System Server and daemons.
     chown system system /sys/power/autosleep