md/raid10: fix: incompatible types in comparison expression (differen…

…t address spaces).

Fixes the following sparse errors in drivers/md/raid10.c error:
incompatible types in comparison expression (different address spaces).

The error was because of the following line in function read_balance():

rdev = rcu_dereference(conf->mirrors[disk].replacement);
    if (rdev == NULL || test_bit(Faulty, &rdev->flags) ||
        r10_bio->devs[slot].addr + sectors > rdev->recovery_offset)
    rdev = rcu_dereference(conf->mirrors[disk].rdev);

Annotating the struct md_rdev *rdev and *replacement in
drivers/md/raid10.h with __rcu fixes the sparse error.

Signed-off-by: YANG LI <abaci-bugfix@linux.alibaba.com>
Reported-by: Abaci <abaci@linux.alibaba.com>

drivers/md/raid10.h

@@ -16,7 +16,8 @@
  */
 
 struct raid10_info {
-	struct md_rdev	*rdev, *replacement;
+	struct md_rdev	__rcu *rdev;
+	struct md_rdev	__rcu *replacement;
 	sector_t	head_position;
 	int		recovery_disabled;	/* matches
 						 * mddev->recovery_disabled