btrfs: zoned: fix a leaked bioc in read_zone_info

The bioc would leak on the normal completion path and also on the RAID56
check (but that one won't happen in practice due to the invalid
combination with zoned mode).

Fixes: 7db1c5d1 ("btrfs: zoned: support dev-replace in zoned filesystems")
CC: stable@vger.kernel.org # 5.16+
Reviewed-by: NAnand Jain <anand.jain@oracle.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>
[ update changelog ]
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

fs/btrfs/zoned.c

@@ -1736,12 +1736,14 @@ static int read_zone_info(struct btrfs_fs_info *fs_info, u64 logical,
 	ret = btrfs_map_sblock(fs_info, BTRFS_MAP_GET_READ_MIRRORS, logical,
 			       &mapped_length, &bioc);
 	if (ret || !bioc || mapped_length < PAGE_SIZE) {
-		btrfs_put_bioc(bioc);
-		return -EIO;
+		ret = -EIO;
+		goto out_put_bioc;
 	}
 
-	if (bioc->map_type & BTRFS_BLOCK_GROUP_RAID56_MASK)
-		return -EINVAL;
+	if (bioc->map_type & BTRFS_BLOCK_GROUP_RAID56_MASK) {
+		ret = -EINVAL;
+		goto out_put_bioc;
+	}
 
 	nofs_flag = memalloc_nofs_save();
 	nmirrors = (int)bioc->num_stripes;
@@ -1760,7 +1762,8 @@ static int read_zone_info(struct btrfs_fs_info *fs_info, u64 logical,
 		break;
 	}
 	memalloc_nofs_restore(nofs_flag);
-
+out_put_bioc:
+	btrfs_put_bioc(bioc);
 	return ret;
 }