btrfs: remove unused raid56 functions which were dedicated for scrub
Since the scrub rework, the following RAID56 functions are no longer
called:
- raid56_add_scrub_pages()
- raid56_alloc_missing_rbio()
- raid56_submit_missing_rbio()
Those functions are all utilized by scrub to handle missing device cases
for RAID56.
However the new scrub code handle them in a completely different way:
- If it's data stripe, go recovery path through btrfs_submit_bio()
- If it's P/Q stripe, it would be handled through
raid56_parity_submit_scrub_rbio()
And that function would handle dev-replace and repair properly.
Thus we can safely remove those functions.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>