These kmaps are thread local and don't need to be atomic.  So they can use
the more efficient kmap_local_page().  However, the mapping of pages in
the stripes and the additional parity and qstripe pages are a bit
trickier because the unmapping must occur in the opposite order from the
mapping.  Furthermore, the pointer array in __raid_recover_end_io() may
get reordered.

Convert these calls to kmap_local_page() taking care to reverse the
unmappings of any page arrays as well as being careful with the mappings
of any special pages such as the parity and qstripe pages.
Signed-off-by: NIra Weiny <ira.weiny@intel.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>