iosched: prevent aliased requests from starving other I/O

Hi, Jens,

If you recall, I posted an RFC patch for this back in July of last year:
http://lkml.org/lkml/2010/7/13/279

The basic problem is that a process can issue a never-ending stream of
async direct I/Os to the same sector on a device, thus starving out
other I/O in the system (due to the way the alias handling works in both
cfq and deadline).  The solution I proposed back then was to start
dispatching from the fifo after a certain number of aliases had been
dispatched.  Vivek asked why we had to treat aliases differently at all,
and I never had a good answer.  So, I put together a simple patch which
allows aliases to be added to the rb tree (it adds them to the right,
though that doesn't matter as the order isn't guaranteed anyway).  I
think this is the preferred solution, as it doesn't break up time slices
in CFQ or batches in deadline.  I've tested it, and it does solve the
starvation issue.  Let me know what you think.

Cheers,
Jeff

Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
GPU: Overclock 2D and 3D gpu. set GPU Bus to match requirements of GPU clock
LED: dynamic LED brightness
HEADSET: force headset notifications single threaded
Fix compilation
 Badass GPU scaling (Show-p1984)
CPU: linaro arm topology drivers
Reduced Android Logger RAM usage

TNX to sakindia123 at xda for point.

Conflicts:
drivers/staging/android/logger.c
CPU OC
Linux 3.0.82
Signed-off-by: pjoyrom <pjoyrom@gmail.com>
Linux 3.0.83
Signed-off-by: pjoyrom <pjoyrom@gmail.com>
Linux 3.0.84
Merge pull request #1 from poppy1/jellybean

Jellybean
merge fix

Change-Id: I1afac330ec321e7d157443d741be067c59e7b7f2