Fix nasty 32-bit overflow bug in buffer i/o code.

On 32-bit architectures, the legacy buffer_head functions are not always
handling the sector number with the proper 64-bit types, and will thus
fail on 4TB+ disks.

Any code that uses __getblk() (and thus bread(), breadahead(),
sb_bread(), sb_breadahead(), sb_getblk()), and calls it using a 64-bit
block on a 32-bit arch (where "long" is 32-bit) causes an inifinite loop
in __getblk_slow() with an infinite stream of errors logged to dmesg
like this:

__find_get_block_slow() failed. block=6740375944, b_blocknr=2445408648
b_state=0x00000020, b_size=512
device sda1 blocksize: 512

Note how in hex block is 0x191C1F988 and b_blocknr is 0x91C1F988 i.e.
the
top 32-bits are missing (in this case the 0x1 at the top).

This is because grow_dev_page() is broken and has a 32-bit overflow due
to shifting the page index value (a pgoff_t - which is just 32 bits on
32-bit architectures) left-shifted as the block number.  But the top
bits to get lost as the pgoff_t is not type cast to sector_t / 64-bit
before the shift.

This patch fixes this issue by type casting "index" to sector_t before
doing the left shift.

Note this is not a theoretical bug but has been seen in the field on a
4TiB hard drive with logical sector size 512 bytes.

This patch has been verified to fix the infinite loop problem on
3.17-rc5
kernel using a 4TB disk image mounted using "-o loop".  Without this
patch
doing a "find /nt" where /nt is an NTFS volume causes the inifinite loop
100% reproducibly whilst with the patch it works fine as expected.

Signed-off-by: Anton Altaparmakov <aia21@cantab.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
cpufreq: Add interface to set/get min/max freq

* Interface similar to that for setting governor.
* Interface can be used by drivers to change/get
  min/max freq per cpu.

Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
msm: limiter: Simplify and debugify min/max freq

* 5echo2@xda reported that sibling cores may or may not
  get updated with required max freq after every resume
  operation.
* This patch make use of hooks added in cpufreq driver.
  These hooks save desired min/max freq if CPU is
  offline OR update min/max freq if CPU is online
  and thus sibling cores will have their proper scaling
  frequencies updated whenever called.
* Also live_min_freq and live_max_freq are added per-cpu
  to help user retrieve actual min/max per cpu.

Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>