CPU hotplug, writeback: Don't call writeback_set_ratelimit() too often during hotplug

The CPU hotplug callback related to writeback calls writeback_set_ratelimit()
during every state change in the hotplug sequence. This is unnecessary
since num_online_cpus() changes only once during the entire hotplug operation.

So invoke the function only once per hotplug, thereby avoiding the
unnecessary repetition of those costly calculations.

Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: Francisco Franco <franciscofranco.1990@gmail.com>
writeback: remove nr_pages_dirtied arg from balance_dirty_pages_ratelimited_nr()

There is no reason to pass the nr_pages_dirtied argument, because
nr_pages_dirtied value from the caller is unused in
balance_dirty_pages_ratelimited_nr().

Signed-off-by: Namjae Jeon <linkinjeon@gmail.com>
Signed-off-by: Vivek Trivedi <vtrivedi018@gmail.com>
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>
Signed-off-by: Francisco Franco <franciscofranco.1990@gmail.com>
msm_otg: remove initialization wake_lock
mm: optimize Kernel Samepage Merging(KSM)
mm: Adjust dirty writeback for IO boost
mm: Modify page_alloc to analyze zone for NULL condition before passing it on to fucntions like zone_dirty_ok.

This is trying to prevent:
Unable to handle kernel NULL pointer dereference
at virtual address 00000001' condition from PC is
at get_page_from_freelist+0xe8/0x630
LR is at zone_dirty_ok+0x18/0xe0
fs: remove some dmesg logspam from Linux mainline 3.4
fs: Modify writeback to make sure block_dump is greater than 1 rather than greater than 0 for android devices
cpufreq: interactive: Sync with latest from Google
cpufreq: interactive: set DEFAULT_TARGET_LOAD 85
Add ZEN Scheduler
zen-iosched: Fix warning: initialization from incompatible pointer type
zen-iosched: Fix Freeze problem
Add SIOPLUS Scheduler
Add VR Scheduler
sioplus-iosched: tuning for performance
ext4: create a new BH_Verified flag to avoid unnecessary metadata validation

Create a new BH_Verified flag to indicate that we've verified all the
data in a buffer_head for correctness.  This allows us to bypass
expensive verification steps when they are not necessary without
missing them when they are.

Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
ext4: change on-disk layout to support extended metadata checksumming

Define flags and change structure definitions to allow checksumming of
ext4 metadata.

Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
ext4: record the checksum algorithm in use in the superblock

Record the type of checksum algorithm we're using for metadata in the
superblock, in case we ever want/need to change the algorithm.

Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
ext4: load the crc32c driver if necessary

Obtain a reference to the cryptoapi and crc32c if we mount a
filesystem with metadata checksumming enabled.

Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>