init: add MountHandler property handler
Set properties dev.mnt.blk.<mount_point>=<device_block_class> for mount
and umount operations by setting up an Epoll handler to catch
EPOLLERR or EPOLLPRI signals when /proc/mounts is changed. Only
update properties associated with block devices. For the mount
point of /, use the designation of /root instead.
Can use the properties in init rc expansion like:
on property dev.mnt.blk.root=*
write /sys/block/${dev.mnt.blk.root}/queue/read_ahead_kb ${boot_read_ahead_kb:-2048}
on property dev.mnt.blk.data=*
write /sys/block/${dev.mnt.blk.data}/queue/read_ahead_kb ${boot_read_ahead_kb:-2048}
on late-fs
setprop boot_read_ahead_kb 128
write /sys/block/${dev.mnt.blk.root}/queue/read_ahead_kb ${boot_read_ahead_kb}
write /sys/block/${dev.mnt.blk.data}/queue/read_ahead_kb ${boot_read_ahead_kb}
Test: boot and inspect getprop results.
Bug: 124072565
Change-Id: I1b8aff44f922ba372cd926de2919c215c40ee874
diff --git a/init/Android.bp b/init/Android.bp
index 9aeb837..8a0bb55 100644
--- a/init/Android.bp
+++ b/init/Android.bp
@@ -110,6 +110,7 @@
"init.cpp",
"keychords.cpp",
"modalias_handler.cpp",
+ "mount_handler.cpp",
"mount_namespace.cpp",
"parser.cpp",
"persistent_properties.cpp",