Introduce a new header, kernel-lib/raid56.h, for later raid56 works.
It contains 2 functions, from original btrfs-progs code:
void raid6_gen_syndrome(int disks, size_t bytes, void **ptrs);
int raid5_gen_result(int nr_devs, size_t stripe_len, int dest, void **data);
Will be expanded later and some part of it(RAID6 recover part) may keep
sync with kernel later.
Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
[ unify gpl header, rename header macro ]
Signed-off-by: David Sterba <dsterba@suse.com>