btrfs: raid56: fix stripes if vertical errors are found

We take two stripe numbers if vertical errors are found.  In case it is
just a pstripe it does not matter but in case of raid 6 it matters as
both stripes need to be fixed.

Fixes: 7a31507 ("btrfs: raid56: do data csum verification during RMW cycle")
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Tanmay Bhushan <007047221b@gmail.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/raid56.c

@@ -1886,7 +1886,7 @@ static int recover_vertical(struct btrfs_raid_bio *rbio, int sector_nr,
 		sector->uptodate = 1;
 	}
 	if (failb >= 0) {
-		ret = verify_one_sector(rbio, faila, sector_nr);
+		ret = verify_one_sector(rbio, failb, sector_nr);
 		if (ret < 0)
 			goto cleanup;