port from msm:
This fixes the issue where LCD takes a long time to come back up
since the execution of backlight on and late_resume works by the
suspend worker thread is delayed due to one (or more) of the
sys_sync calls in early_suspend and suspend paths taking a long
time (sometimes 15sec or more) for the below reported scenario(s):
Scenario 1 (copy with usb connected):
1. plug usb
2. adb shell
3. busybox cp /sdcard/file1 /sdcard/file2 (copy >= 100MB file1
in sdcard/emmc to file2 in sdcard/emmc)
4. press end key to suspend
5. press end key again and it takes a long time for LCD to come
back up
Scenario 2 (background copy):
1. plug usb
2. adb shell
3. busybox cp /sdcard/file1 /sdcard/file2 & (copy >= 100MB file1
in sdcard/emmc to file2 in sdcard/emmc)
4. disconnect usb
5. press end key to suspend
6. press end key again and it takes a long time for LCD to come
back up
A more common form of Scenario 2 is for the user to just use the
copy function on the UI to copy large file(s).
We address this by moving sys_sync calls to a separate workqueue
and having a timeout polling based mechanism to bail out of suspend
in case of user invoking a wakeup event (like end key press) while
we are waiting for the sys_sync completion at the synchronization
point in suspend worker thread context.
When ion_vma_open is called, a reference to the handle in
the vma must be taken. Otherwise, if forking occurs,
ion_vma_close will be called twice which will leave one of
the calls with an invalid reference.
Fix bug: operation and event cannot work concurrently.
remove/rename a file in android file explorer during coping/receiving
a large file to/from mtp device from pc, after all the operations
done, change in android would be ignore in pc explorer, because
file change event was block by the long operation and failed to send to
pc.
