exofs: Remove unused data_map member from exofs_sb_info

The struct pnfs_osd_data_map data_map member of exofs_sb_info was
never used after mount. In fact all it's members were duplicated
by the ore_layout structure. So just remove the duplicated information.

Also removed some stupid, but perfectly supported, restrictions on
layout parameters. The case where num_devices is not divisible by
mirror_count+1 is perfectly fine since the rotating device view
will eventually use all the devices it can get.

Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
Signed-off-by: Benny Halevy <bhalevy@tonian.com>

include/scsi/osd_ore.h

@@ -34,6 +34,8 @@ struct ore_comp {
 
 struct ore_layout {
 	/* Our way of looking at the data_map */
+	enum pnfs_osd_raid_algorithm4
+		 raid_algorithm;
 	unsigned stripe_unit;
 	unsigned mirrors_p1;