zloop: make the write pointer of full zones invalid

commit 866d657 upstream.

The write pointer of zones that are in the full condition is always
invalid. Reflect that fact by setting the write pointer of full zones
to ULLONG_MAX.

Fixes: eb0570c ("block: new zoned loop block device driver")
Cc: stable@vger.kernel.org
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: damien-lemoal

drivers/block/zloop.c

@@ -177,7 +177,7 @@ static int zloop_update_seq_zone(struct zloop_device *zlo, unsigned int zone_no)
 		zone->wp = zone->start;
 	} else if (file_sectors == zlo->zone_capacity) {
 		zone->cond = BLK_ZONE_COND_FULL;
-		zone->wp = zone->start + zlo->zone_size;
+		zone->wp = ULLONG_MAX;
 	} else {
 		zone->cond = BLK_ZONE_COND_CLOSED;
 		zone->wp = zone->start + file_sectors;
@@ -326,7 +326,7 @@ static int zloop_finish_zone(struct zloop_device *zlo, unsigned int zone_no)
 	}
 
 	zone->cond = BLK_ZONE_COND_FULL;
-	zone->wp = zone->start + zlo->zone_size;
+	zone->wp = ULLONG_MAX;
 	clear_bit(ZLOOP_ZONE_SEQ_ERROR, &zone->flags);
 
  unlock:
@@ -437,8 +437,10 @@ static void zloop_rw(struct zloop_cmd *cmd)
 		 * copmpletes.
 		 */
 		zone->wp += nr_sectors;
-		if (zone->wp == zone_end)
+		if (zone->wp == zone_end) {
 			zone->cond = BLK_ZONE_COND_FULL;
+			zone->wp = ULLONG_MAX;
+		}
 	}
 
 	rq_for_each_bvec(tmp, rq, rq_iter)