md/raid10: round up to bdev_logical_block_size in narrow_write_error.

RAID10 version of earlier fix for RAID1.  We must never initiate
IO with sizes less that logical_block_size.
Signed-off-by: NNeilBrown <neilb@suse.de>

drivers/md/raid10.c

@@ -2572,7 +2572,8 @@ static int narrow_write_error(struct r10bio *r10_bio, int i)
 	if (rdev->badblocks.shift < 0)
 		return 0;
 
-	block_sectors = 1 << rdev->badblocks.shift;
+	block_sectors = roundup(1 << rdev->badblocks.shift,
+				bdev_logical_block_size(rdev->bdev) >> 9);
 	sector = r10_bio->sector;
 	sectors = ((r10_bio->sector + block_sectors)
 		   & ~(sector_t)(block_sectors - 1))