linux-phytec-fsl

f2fs crypto: zero next free dnode block

Now page cache of meta inode is used by garbage collection for encrypted page,
it may contain random data, so we should zero it before issuing discard.

Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>