btrfs: zoned: move non-changing condition check out of the loop

btrfs_zone_activate() checks if block_group->alloc_offset ==
block_group->zone_capacity every time it iterates the loop. But, it is
not depending on the index. Move out the check and do it only once.

Fixes: f9a912a3 ("btrfs: zoned: make zone activation multi stripe capable")
Reviewed-by: NJohannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: NNaohiro Aota <naohiro.aota@wdc.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

fs/btrfs/zoned.c

@@ -1835,6 +1835,12 @@ bool btrfs_zone_activate(struct btrfs_block_group *block_group)
 		goto out_unlock;
 	}
 
+	/* No space left */
+	if (block_group->alloc_offset == block_group->zone_capacity) {
+		ret = false;
+		goto out_unlock;
+	}
+
 	for (i = 0; i < map->num_stripes; i++) {
 		device = map->stripes[i].dev;
 		physical = map->stripes[i].physical;
@@ -1842,12 +1848,6 @@ bool btrfs_zone_activate(struct btrfs_block_group *block_group)
 		if (device->zone_info->max_active_zones == 0)
 			continue;
 
-		/* No space left */
-		if (block_group->alloc_offset == block_group->zone_capacity) {
-			ret = false;
-			goto out_unlock;
-		}
-
 		if (!btrfs_dev_set_active_zone(device, physical)) {
 			/* Cannot activate the zone */
 			ret = false;