writeback: fix occasional slow sync(1)
In case when system contains no dirty pages, wakeup_flusher_threads() will
submit WB_SYNC_NONE writeback for 0 pages so wb_writeback() exits
immediately without doing anything, even though there are dirty inodes in
the system.  Thus sync(1) will write all the dirty inodes from a
WB_SYNC_ALL writeback pass which is slow.

Fix the problem by using get_nr_dirty_pages() in wakeup_flusher_threads()
instead of calculating number of dirty pages manually.  That function also
takes number of dirty inodes into account.

Change-Id: Ic90f80a31bb866b7628143b8b013871f83d05c13
Signed-off-by: Jan Kara <jack@suse.cz>
Reported-by: Paul Taysom <taysom@chromium.org>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
cpufreq: Add cpu-boost driver

When certain bursty and important events take place, it might take a while
for the current cpufreq governor to notice the new load and react to it.
That would result in poor user experience. To alleviate this, the cpu-boost
driver boosts the frequency of a CPU for a short duration to maintain good
user experience while the governor catches up.

Specifically, this commit deals with ensuring that when "important" tasks
migrate from a fast CPU to a slow CPU, the frequency of the slow CPU is
boosted to be at least as high as the fast CPU for a short duration.

Since this driver enforces the boost by hooking into standard cpufreq
ADJUST notifiers, it has several advantages:
- More portable across kernel versions where the cpufreq internals might
  have been rewritten.
- Governor agnostic and hence works with multiple governors like
  conservative, ondemand, interactive, etc.
- Does not affect the sampling period/logic of existing governors.
- Can have the boost period adjusted independent of governor sampling
  period.

Signed-off-by: Saravana Kannan <skannan@codeaurora.org>

Change-Id: Ibd814a20043d0aba64ee7637a4a79b9ffa1b0991
cpufreq: Add a sync limit to cpu-boost

Perform frequency synchronization only when source CPU's frequency
is less than sync_threshold, else sync to the sync_threshold.

Signed-off-by: Rohit Gupta <rohgup@codeaurora.org>

Change-Id: I544c414568d4e015b80ce5891dd215275bac95da
cpu boost: backport missing functions from 3.4 (DerTeufel)
reference: http://webcache.googleusercontent.com/search?q=cache:7y4Vnjzxo6wJ:androidfilesgit.org/MaC/android_kernel_jewel/commit/8e9f9bdc0bb75222891cb39389fef6910dcb085d.diff+&cd=1&hl=en&ct=clnk&gl=il

thx to dorimanx for commiting cpu boost to his 3.12 kernel. i would have missed this driver without him

Change-Id: I3cd786129f7eff14bb775194919c803566e07f25
switch do_fsync() to fget_light()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
async fsync from htc one (ported by faux123) + version 2.2.3

Change-Id: Id82359eae3a5f1e6060308a8df76a101d6ea5407
async fsync Kconfig fix

Change-Id: I2a7d4c1f7de149419a578a7bb661bf39612f7050
wifi: block ipv6

Change-Id: Ie755d5ee63482412bf6238a27691f4fed4692354
removed interceptor from drivers makefile

from DerTeufel
Revert "removed interceptor from drivers makefile"

This reverts commit c486c8b44b735aa8e86e5972c6d1ead28bd5e51a.
Revert "wifi: block ipv6"

This reverts commit ab0d588cb84c63e4f1204233386f8f170c410c48.
Revert "async fsync Kconfig fix"

This reverts commit 35c0ace867f1d3ba1dcef4387933e87e2c89a974.
Revert "async fsync from htc one (ported by faux123) + version 2.2.3"

This reverts commit 6cb2ecc0174eb9949660459178551d5de4471be4.
Revert "Revert "wifi: block ipv6""

This reverts commit 4b39d698b4850d42c6199175544024a591d52570.
implemented BFQ-v5r1 block IO scheduler
block: update BFQ I/O scheduler to v6r2 for 3.0.y

BFQ uses struct cfq_io_context to store its per-process per-device data,
reusing the same code for cic handling of CFQ.  The code is not shared
ATM to minimize the impact of these patches.

This patch introduces a new hlist to each io_context to store all the
cic's allocated by BFQ to allow calling the right destructor on module
unload; the radix tree used for cic lookup needs to be duplicated
because it can contain dead keys inserted by a scheduler and later
retrieved by the other one.

Update the io_context exit and free paths to take care also of
the BFQ cic's.

Change the type of cfqq inside struct cfq_io_context to void *
to use it also for BFQ per-queue data.

A new bfq-specific ioprio_changed field is necessary, too, to avoid
clobbering cfq's one, so switch ioprio_changed to a bitmap, with one
element per scheduler.

Signed-off-by: Paolo Valente <paolo.valente@unimore.it>
Signed-off-by: Arianna Avanzini <avanzini.arianna@gmail.com>
block: row-iosched idling triggered by readahead pages

In the current implementation idling is triggered only by request
insertion frequency. This heuristic is not very accurate and may hit
random requests that shouldn't trigger idling. This patch uses the
PG_readahead flag in struct page's flags, which indicates that the page
is part of a readahead window, to start idling upon dispatch of a request
associated with a readahead page.

The above readehead flag is used together with the existing
insertion-frequency trigger. The frequency timer will catch read requests
which are not part of a readahead window, but are still part of a
sequential stream (and therefore dispatched in small time intervals).

Change-Id: Icb7145199c007408de3f267645ccb842e051fd00
Signed-off-by: Lee Susman <lsusman@codeaurora.org>
block: row: change hrtimer_cancel to hrtimer_try_to_cancel

Calling hrtimer_cancel with interrupts disabled can result in a livelock.
When flushing plug list in the block layer interrupts are disabled and an
hrtimer is used when adding requests from that plug list to the scheduler.
In this code flow, if the hrtimer (which is used for idling) is set, it's
being canceled by calling hrtimer_cancel. hrtimer_cancel will perform
the following in an endless loop:
1. try cancel the timer
2. if fails - rest_cpu
the cancellation can fail if the timer function already started. Since
interrupts are disabled it can never complete.
This patch reduced the number of times the hrtimer lock is taken while
interrupts are disabled by calling hrtimer_try_co_cancel. the later will
try to cancel the timer just once and return with an error code if fails.

CRs-fixed: 499887
Change-Id: I25f79c357426d72ad67c261ce7cb503ae97dc7b9
Signed-off-by: Tatyana Brokhman <tlinder@codeaurora.org>
block: row: Remove warning massage from add_request

Regular priority queues is marked as "starved" if it skipped a dispatch
due to being empty. When a new request is added to a "starved" queue
it will be marked as urgent.
The removed WARN_ON was warning about an impossible case when a regular
priority (read) queue was marked as starved but wasn't empty. This is
a possible case due to the bellow:
If the device driver fetched a read request that is pending for
transmission and an URGENT request arrives, the fetched read will be
reinserted back to the scheduler. Its possible that the queue it will be
reinserted to was marked as "starved" in the meanwhile due to being empty.

CRs-fixed: 517800
Change-Id: Iaae642ea0ed9c817c41745b0e8ae2217cc684f0c
Signed-off-by: Tatyana Brokhman <tlinder@codeaurora.org>
block: add runtime pm helpers

Add runtime pm helper functions:

void blk_pm_runtime_init(struct request_queue *q, struct device *dev)
  - Initialization function for drivers to call.

int blk_pre_runtime_suspend(struct request_queue *q)
  - If any requests are in the queue, mark last busy and return -EBUSY.
    Otherwise set q->rpm_status to RPM_SUSPENDING and return 0.

void blk_post_runtime_suspend(struct request_queue *q, int err)
  - If the suspend succeeded then set q->rpm_status to RPM_SUSPENDED.
    Otherwise set it to RPM_ACTIVE and mark last busy.

void blk_pre_runtime_resume(struct request_queue *q)
  - Set q->rpm_status to RPM_RESUMING.

void blk_post_runtime_resume(struct request_queue *q, int err)
  - If the resume succeeded then set q->rpm_status to RPM_ACTIVE
    and call __blk_run_queue, then mark last busy and autosuspend.
    Otherwise set q->rpm_status to RPM_SUSPENDED.

The idea and API is designed by Alan Stern and described here:
http://marc.info/?l=linux-scsi&m=133727953625963&w=2

Change-Id: I486612af79c7887116f70a4fde552c107f7fa360
Signed-off-by: Lin Ming <ming.m.lin@intel.com>
Signed-off-by: Aaron Lu <aaron.lu@intel.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Git-commit: 6c9546675864f51506af69eca388e5d922942c56
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
Signed-off-by: Sujit Reddy Thumma <sthumma@codeaurora.org>