btrfs: fix chunk map leak in btrfs_map_block() after btrfs_chunk_map_num_copies()

Fix a chunk map leak in btrfs_map_block(): if we return early with -EINVAL,
we're not freeing the chunk map that we've just looked up.

Fixes: 0ae653f ("btrfs: reduce chunk_map lookups in btrfs_map_block()")
CC: stable@vger.kernel.org # 6.12+
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Mark Harmstone <mark@harmstone.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Author: maharmstone

fs/btrfs/volumes.c

@@ -6921,8 +6921,10 @@ int btrfs_map_block(struct btrfs_fs_info *fs_info, enum btrfs_map_op op,
 	}
 
 	num_copies = btrfs_chunk_map_num_copies(map);
-	if (io_geom.mirror_num > num_copies)
-		return -EINVAL;
+	if (io_geom.mirror_num > num_copies) {
+		ret = -EINVAL;
+		goto out;
+	}
 
 	map_offset = logical - map->start;
 	io_geom.raid56_full_stripe_start = (u64)-1;