fs: Add F2FS support

fs: Add F2FS support

"F2FS (Flash-Friendly File System) is flash-friendly file system which was merged
into Linux kernel v3.8 in 2013.

The motive for F2FS was to build a file system that from the start, takes into
account the characteristics of NAND flash memory-based storage devices (such as
solid-state disks, eMMC, and SD cards).

F2FS was designed on a basis of a log-structured file system approach, which
remedies some known issues of the older log structured file systems, such as
the snowball effect of wandering trees and high cleaning overhead. In addition,
since a NAND-based storage device shows different characteristics according to
its internal geometry or flash memory management scheme (such as the Flash
Translation Layer or FTL), it supports various parameters not only for
configuring on-disk layout, but also for selecting allocation and cleaning
algorithm.", quote by https://en.wikipedia.org/wiki/F2FS.

The source codes for F2FS are available from:

http://git.kernel.org/cgit/linux/kernel/git/jaegeuk/f2fs.git
http://git.kernel.org/cgit/linux/kernel/git/jaegeuk/f2fs-tools.git

This patch has been integrated in OpenMandriva Lx 3.
  https://www.openmandriva.org/

Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Pete Batard <pete@akeo.ie>
Signed-off-by: Daniel Kiper <daniel.kiper@oracle.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>