init.rc: use /sys/class/block instead of /sys/devices/virtual/block

/sys/class/block covers all of dm-[0-9], sd[a-z], mmcblk[0-9].
Use it instead of /sys/devices/virtual/block, which only covers dm
devices.

This allows f2fs tunings to be applied more reliably regardless of
how the userdata partition is set up.

Test: Confirm entries under /dev/sys aren't dangling and cp_interval,
      gc_urgent_sleep_time, iostat_enable and discard_max_bytes are
      all set up properly under FBE, FDE and unencrypted.
Change-Id: I089af5bc068445f33919df6659671e50456d49f9
Signed-off-by: Juhyung Park <qkrwngud825@gmail.com>

Author: arter97

rootdir/init.rc

@@ -1022,13 +1022,13 @@ on boot
     chown root system /sys/block/zram0/writeback
     chmod 0664 /sys/block/zram0/writeback
 
-    # to access F2FS sysfs on dm-<num> directly
+    # to access F2FS userdata partition sysfs directly
     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
+    # to access userdata device sysfs
     mkdir /dev/sys/block/by-name 0755 system system
-    symlink /sys/devices/virtual/block/${dev.mnt.dev.data} /dev/sys/block/by-name/userdata
+    symlink /sys/class/block/${dev.mnt.blk.data} /dev/sys/block/by-name/userdata
 
     # F2FS tuning. Set cp_interval larger than dirty_expire_centisecs, 30 secs,
     # to avoid power consumption when system becomes mostly idle. Be careful
@@ -1039,8 +1039,7 @@ on boot
     write /dev/sys/fs/by-name/userdata/iostat_enable 1
 
     # 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
+    # for filesystem tuning first
     write /dev/sys/block/by-name/userdata/queue/discard_max_bytes 134217728
 
     # Permissions for System Server and daemons.