ext4: speed up truncate/unlink by not using bforget() unless needed

Do not iterate over data blocks scanning for bh's to forget as they're
never exist. This improves time taken by unlink / truncate syscall.
Tested by continuously truncating file that is being written by dd.
Another test is rm -rf of linux tree while tar unpacks it. With
ordered data mode condition unlikely(!tbh) was always met in
ext4_free_blocks. With journal data mode tbh was found only few times,
so optimisation is also possible.

Unlinking fallocated 60G file after doing sync && echo 3 >
/proc/sys/vm/drop_caches && time rm --help

X86 before (linux 3.6-rc4):
real    0m2.710s
user    0m0.000s
sys     0m1.530s

X86 after:
real    0m0.644s
user    0m0.003s
sys     0m0.060s

MIPS before (linux 2.6.37):
real    0m 4.93s
user    0m 0.00s
sys     0m 4.61s

MIPS after:
real    0m 0.16s
user    0m 0.00s
sys     0m 0.06s

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Andrey Sidorov <qrxd43@motorola.com>
Signed-off-by: franciscofranco <franciscofranco.1990@gmail.com>

Change-Id: Ie78a945cb82b3892eaf88701f2dc3b7726104fb5
msm: dma: Moving queue_work() function within spinlock

Currently we are adding a dma command to the staged list with in a
spinlock and then adding to workqueue using queue_work after unlocking
the spinlock. With this there is chance of executing DMA commands in out
of order in below concurrency case.

Tread1                                Thread2
__msm_dmov_enqueue_cmd_ext
   spin_lock_irqsave(..)
   list_add_tail(..)
   spin_unlock_irqrestore(..)
       --PREEMPT--
                                      __msm_dmov_enqueue_cmd_ext
                                         spin_lock_irqsave(..)
                                         list_add_tail(..)
                                         spin_unlock_irqrestore(..)
                                         queue_work()
                                         ..
   queue_work()
So adding queue_work with in spin_lock will make sure that the
work added in the work_queue is processed in the same order as they
are added in staged_commands.

CRs-Fixed: 423190
Change-Id: I2ffd1327fb5f0cd1f06db7de9c026d1c4997fe4d
Acked-by: Gopi Krishna Nedanuri <gnedanur@qti.qualcomm.com>
Signed-off-by: Utsab Bose <ubose@codeaurora.org>